Ellenberger could not find a way to close the distance and the taller MacDonald punched away from the outside. It was effective if not entertaining and the crowd of 7,816 at KeyArena booed loudly for much of the fight.
The bout may go down as one of the worst received UFC co-main events, judging from the fan response throughout. The 30-27, 29-28, 30-27 decision was greeted by even more boos.
"That fight sucked so bad," said UFC president Dana White, who was frustrated earlier in the card by inconsistent judging.
One could argue it was smart strategy by MacDonald. It forced Ellenberger into facing the risk/reward of closing the gap. And MacDonald is trained by Firas Zahabi, a master of the jab.
Champion Georges St-Pierre, who also works under Zahabi in the same Montreal gym as MacDonald, was likely nodding in appreciation from his viewing position. St-Pierre — who takes on No 1 contender Johny Hendricks in November — and MacDonald have said they won't fight each other but the day of reckoning is approaching.
Carlos (Natural Born Killer) Condit and Martin (The Hitman) Kampman meet next month in another welterweight fight with title contender implications.
"I think I did exactly what I was supposed to do. I kept up my end," MacDonald said. "He's a counter-puncher, and a very powerful puncher. I was waiting for my opportunities and he wasn't coming in at the right times."
In Saturday's main event, flyweight champion Demetrious (Mighty Mouse) Johnson put on a show in submitting challenger John Moraga via armbar at 3:43 of the fifth round. The champ transitioned slickly from kimura to armbar in forcing Moraga to tap with his arm bent at an ugly angle.
The move earned Johnson US$50,000 for submission of the night.
It was a dominant display, with Johnson's superior grappling and speed winning the day. It was also the latest stoppage in the history of the UFC.
In the aftermath of MacDonald-Ellenberger, White said he hoped the 125-pound title bout would "slap the bad taste out of everyone's mouth."
The little men did their best with the five-foot-three Johnson, who makes his home in nearby Parkland, taking the upper hand with his takedowns of the five-foot-six Moraga.
The challenger, a relative unknown in the fledgling division, showed his teeth with a triangle attempt in the second round but Johnson (18-2-1) outmanoeuvred him and Moraga (13-2) went back to his stool frustrated. Off another takedown, Johnson almost locked in a kimura in the third round.
It was more of the same in the fourth and fifth with Johnson controlling the fight — and Moraga.
MacDonald, a native of Kelowna, B.C., who fights out of Montreal, came into his bout ranked No. 3 in the 170-pound ranks while Ellenberger, a former U.S. marine who had done a lot of trash-talking at MacDonald's expense, was No. 4.
The two fighters did shake hands after the decision, which stretched MacDonald's win streak to five.
Ellenberger (29-7) was clearly feeling confident going into the evening, tweeting a picture of himself in the Hugo Boss suit he planned to wear at the post-fight news conference.
Ellenberger came out first to "Bleed it out" by Linkin Park. MacDonald followed to Rihanna and a mixture of boos and cheers. The Canadian looked like he couldn't wait to fight, staring at Ellenberger as he entered the cage.
Ellenberger had trouble closing the distance in the first round and MacDonald's stinging jab didn't help. The crowd didn't like the round but MacDonald (15-1) probably did.
There were more boos in the second as MacDonald waited for Ellenberger to try to come in. Ellenberger's face began to show damage.
MacDonald used kicks and jabs to keep Ellenberger away. But he couldn't stop everything and was bleeding from the face in the third round. Ellenberger also managed a late takedown, winning cheers for his effort.
"It just wasn't my night," said Ellenberger. "I didn't have a good night. I didn't pull the trigger."
"I'm very disappointed in myself," he added.
White thought both co-main event fighters failed to impress — Ellenberger because he froze and MacDonald because he didn't press his advantage.
"I don't think he did anything," White said of MacDonald. "He threw a few jabs and some front kicks. That's all he did.
"I don't think he moved down the (rankings) ladder but do you think anyone's screaming to see him in a fight again?"
Bantamweight Liz (Girlrilla) Carmouche battered pint-sized Brazilian Jessica Andrade en route to a second-round TKO in the first UFC matchup of two openly lesbian fighters.
Carmouche (8-3) survived a first-round guillotine choke attempt from the five-foot-two Andrade (9-3). But it was all Carmouche in the second as she alternated between mounting the Brazilian and taking her back, slamming down one ground strike after another until referee Herb Dean stepped in at 3:57.
The biggest cheer during the bout, however, came when women's champion (Rowdy) Ronda Rousey was shown on the big screens.
Earlier, middleweight Ed (Short Fuse) Herman won a split decision over former Strikeforce fighter Trevor (Hot Sauce) Smith in a wild, memorable, free-swinging bout that earned both men a $50,000 bonus for fight of the night.
"Wow... Hell of a fight. Those guys took a few quality years off their lives," tweeted Condit, ranked No. 2 among welterweights.
Both men were wobbled in a hard-hitting first round and Smith was cut around the eye. Smith (10-4) kept swinging and Herman (21-7 with one no contest) never blinked, even when he took a kick to the groin late in the fight.
It really was Sleepless in Seattle as both men refused to go down.
"What a SICK fight much respect to Herman and Smith!!!!!! Tough one to judge," tweeted White.
He was proved right when the judges scored it 30-27, 27-30, 29-28 for Herman. White later tweeted that Smith fought with a broken hand.
"I thought I won, but it was a close fight, so I’ll give him the credit," said Smith, who fights out of Tukwila, Wash.
There were some odd scorecards on the day, with another undercard bout seeing two judges awarding all three rounds to different fighters as Daron (Detroit Superstar) Cruickshank won a split (30-27, 27-30, 30-27) decision over veteran Yves Edwards.
"That was a garbage dec! I hate the way this sport is judged," tweeted lightweight Jamie Varner.
Veteran welterweight (Ruthless) Robbie Lawler floored Bobby (Vicious) Voelker and then stopped him with a right to the head as referee Dan Miragliotta rushed to end the carnage 24 seconds into the second round.
It was all Lawler (21-9 with one no contest), who is 2-0 and has impressed since returning to the UFC. Voelker (24-10), who took the fight on two weeks notice, was game but outgunned.
Lightweight Melvin (The Young Assassin) Guillard, who had lost four of his last five fights, dominated Mac Danzig en route to a nasty knockout at 2:47 of the second round. He won $50,000 for knockout of the night.
Guillard (48-13-3 with one no contest) floored Danzig (22-11-1) with a punch to the head and then put him away with a flurry on the ground before referee Steve Newport finally stepped in.
"The judges rules the Melvin Guillard vs Mac Danzig fight a split dec," White tweeted sarcastically after the stoppage.
"Yes that was a joke," he added.
"Judging is so bad in MMA people actually thought I was serious and that could happen," he continued on Twitter.
Danzig, who has now lost four of his last six UFC fights and seven of his last 10, had trouble regaining his equilibrium and fell over when he finally tried to get off the canvas. But he walked out of the cage under his own steam.
Lightweight Jorge (Gamebred) Masvidal submitted local favourite Michael (Maverick) Chiesa (9-1) via D'Arce choke with just one second remaining in the second round of a hard-fought bout that featured some big punches and plenty of technical grappling.
There has been some bad blood before the fight with Masvidal (25-7) objecting to Chiesa's win over a teammate last time out, not to mention his bushy beard.
Lightweight Danny (Last Call) Castillo (16-5) won a unanimous 29-28 decision over Tim (The Dirty Bird) Means (18-5-1).
Dutch bantamweight Germaine (The Iron Lady) de Randamie (4-2) earned a split (30-27, 28-29, 29-28) decision over Julie (Fireball) Kedzie (16-12) in a battle of UFC newcomers.
"Have no clue how a judge could call that a split dec!!!" tweeted White. "MMA judges scare me. Randamie won easily 2-1 in a not very exciting fight."
Lightweight Justin (J-Bomb) Salas (11-4) won a split (29-28, 28-29, 29-28) decision over veteran Aaron Riley (29-14-1) in a fight that left both men's faces busted up.
Bantamweight Yaotzin Meza (19-8) defeated John (Prince) Albert (7-5) by second-round rear-naked choke.
NOTES — Herman, Riley, Danzig and Andrade all went to the hospital but were brought back and reported to be fine.