Having tipped a long-range Laurent Ciman shot over the crossbar, Clint Irwin could not control a Marco Donadel effort from distance from the resulting corner and Mancosu nodded in the rebound.
Toronto were level on the half-hour mark, though, when Altidore’s left-footed shot squirmed through Montreal goalkeeper Maxime Crepeau with Impact left-back - and former TFC man - Daniel Lovitz down on the turf due to an injury.
The two sides exchanged chances after that, but Montreal had the best one when Ignacio Piatti was brought down by Irwin in the box only for the Argentine to fire the resulting penalty over the crossbar.
Sebastian Giovinco, on as a substitute, also cleared the bar from a good position late on but Toronto will return to BMO Field with a draw and an away goal in the bag.
1. Vanney takes it seriously: I don’t think it should particularly come as a surprise - this is a trophy Toronto should respect both in terms of prestige and reward - but the Reds’ starting XI was about as strong as it could be. Raheem Edwards, Jonathan Osorio and Jordan Hamilton came in to fill the Canadian quota and Irwin replaced Alex Bono in goal, but otherwise Toronto were unchanged from their win over D.C. United.
We’ll see what that forces Vanney to do on Friday, against the New England Revolution, but it shouldn’t wreak havoc on his team selection. If the defence can get through two games in quick succession, the coach has Giovinco and Victor Vazquez to bring back into the lineup and he was always going to be without Michael Bradley anyway.
2. Irwin’s up and down night: Irwin has played one MLS game since March, which begs the question: where is his next game going to come from once the Canadian Championship is over?
This was a mixed evening for the American, who could have dealt with Donadel’s long-range effort better than he did and then conceded a penalty by bringing down Piatti. He then made saves from Ballou Tabla and Ciman, though, to keep TFC level in the tie.
It will be interesting to see how Vanney handles his goalkeepers once this competition is over. Is it worth splitting the starts to keep Irwin sharp, even if Bono will almost certainly be the guy come playoff time?
3. Home advantage matters: From 3-0, to 3-2, to 1-1... Toronto are gradually getting better in these big games in Montreal.
They still haven’t quite figured the Impact out, though; perhaps no other team in MLS is as good at coaxing defensive errors out of Toronto. Biello’s team is fast on the break, reads second balls very well and has the physicality to cause problems in the box, and it continues to cause the Reds trouble.
A 1-1 draw is a good result at Stade Saputo, though, and one Toronto undoubtedly would have taken beforehand. As much as they have struggled to keep a lid on the Impact, TFC will always create chances against a shaky defence and the trophy is now theirs to lose ahead of the return leg at BMO Field.