B.J. Penn, his opponent, was cheered as he entered.
A grim MacDonald weighed in first, tipping the scales at 170.2 pounds, slapping his chest four times while on the scales. Penn walked on next, his eyes locked on the Canadian at the other side of the stage. MacDonald pounded his chest in response.
Penn, a former lightweight and welterweight champion who is 10 years older than the 23-year-old Canadian, weighed in at 168.2 pounds.
UFC president Dana White kept an arm between the two as they faced off. MacDonald seemed to say something to Penn as the Hawaiian moved closer but nothing came of it.
Lightweight champion Benson Henderson weighed in at 154.6 pounds, earning cheers for staying true to his local roots by styling a Gary Payton Sonics' jersey.
Challenger Nate Diaz weighed in at 155.6 pounds on his first attempt and 155.2 on a second attempt. He was given two hours to make 155, which he accomplished.
Fighters are given a one-pound cushion when it comes to making weight, except for championship bouts so Diaz could not exceed the lightweight limit of 155.
Diaz put on a scowl and put up his fist as Henderson came over to his side of the stage to pose. White quickly got his arm in and when he urged them to walk away, Nick Diaz came in to nudge younger brother Nate away from the champion.
In the co-main event, former champion Mauricio (Shogun) Rua was 205 pounds to Alexander (The Mauler) Gustafsson's 205.4.
Bantamweight Rafael Assuncao, who fights Mike Easton, made 136 pounds on his second attempt on the scales.
Lightweight Henry Martinez, who faces Daron Cruickshank, weighed in at 158.8 and failed to make the 156-pound limit on another attempt. He will forfeit 20 per cent of his purse.