The Timbers leapfrogged Vancouver with their 3-0 win over the visiting Whitecaps last weekend to move into the last playoff position in the West, sitting in fifth spot with a 9-8-12 record.
Seventh-place Toronto, which extended its unbeaten streak to two games with a 3-0 win over visiting Chivas USA last weekend, is three points out of the playoff picture in the East with a 10-11-7 record.
"Both teams need the points," said Toronto midfielder Michael Bradley. "And so it's a big game."
A win Saturday would be a single-season franchise-record 11th for Toronto, surpassing the 10 posted in 2009 (10-11-9). It would also push Toronto's points total to 40, one more than the 2009 record.
Both teams will be watching the other weekend results closely.
A Toronto loss coupled with wins by the teams above them will widen the playoff chasm. With a game in hand, Toronto has points available but some missteps by neighbouring sides would help.
First up for TFC are the Timbers, led by dangerous attacker Diego Valeri who has a hand in most of the Portland scoring.
"For me the key is Valeri and knowing where he is at all times," said Toronto coach Greg Vanney.
The Argentine designated player is celebrating his third goal of the week award this season thanks a to a stylish left-footed volley against Vancouver.
"An excellent player," said Toronto captain Steven Caldwell.
"A special player," echoed Toronto goalie Joe Bendik, a former Timber. "They have a lot of good supporting cast as well, but he's kind of what makes it click."
Man-marking Valeri is not an option because the attacking midfielder will drift outside, drawing defenders away while Nagbe moves into space, according to Vanney.
"It's easier to make sure we communicate and pass him on as he goes into certain areas," said Vanney. "He has tendencies. We know what his tendencies are and we're ready for him."
Lose Valeri at your peril. Vancouver did and it led to the goal of the week as he ghosted up the middle.
Going into weekend play, Valeri has nine goals and is tied for second in the league with a career-high 14 assists, which matches the Timbers' MLS franchise single-season record.
Vanney pointed to midfielder-forward Darlington Nagbe as another Portland danger man. Six-foot-four Nigerian forward Fanendo Adi, with eight goals, can also be a handful.
With 52 goals, Portland stands third in the league in offence and has scored three or more in three of its last four league games. Things have been more chaotic at the other end where the Timbers have given up 48 goals this season to rank 15th in the league.
Portland has five players with six goals or more (including Canadian captain Will Johnson) while Toronto has three — and is still missing leading scorer Jermain Defoe.
Vanney and his players point to progress in recent weeks, citing a 1-1 tie in Chicago two weeks ago as a starting point for the reversal in form. Toronto was denied a win against the Fire by an erroneous call from the official but showed resolve in its fightback.
Against Chivas last week, two of the goals came off set plays which had been worked on at the training ground.
"We're definitely making progress," said Vanney.
With an early kickoff and traffic snarls expected, Toronto FC players will be spending the night in a hotel ahead of Saturday's 1 p.m. kickoff. Vanney said the hotel idea came from some of the players.
"The one o'clock game here is nice," said Bendik. "You just wake up and go. You don't have to think about anything."
Bendik sees the benefits of the hotel stay but says the timing is not that great for him this week. His family is visiting.
Toronto hopes the early kickoff will not be welcomed by its West Coast opposition. The Timbers flew in Friday.
Getting in and out of BMO Field will be complicated by the weekend closure of the nearby Gardiner Expressway.
Toronto will be missing Defoe (groin) and midfielder Collen Warner (hamstring) while Brazilian midfielder Jackson is suspended following his red card last weekend.
Portland is unbeaten in six games in all competitions, with a reserve side thumping Guyana's Alpha United 6-0 at Providence Park on Tuesday in the CONCACAF Champions League.
"It's a very dangerous game," defender-midfielder Rodney Wallace told the Portland team website this week. "They're a good team, they're in a situation right now in many ways similar to ours. We know it's not going to be easy but we also know we have to take care of business in Toronto."
NOTES — Portland has never won in Toronto, managing only a tie and a loss ... Johnson returns to the Timbers lineup after a one-game suspension. Despite that ban, Portland coach Caleb Porter has used just 13 different players over the last four games.
Follow @NeilMDavidson on Twitter.