TORONTO – Ahead of two of the biggest nights in club history loom plenty of questions and concerns.

As Toronto FC brace for the start of the 2018 Concacaf Champions League final against Chivas de Guadalajara on Tuesday at BMO Field (8:15 pm ET; TSN2 in Canada | UDN, go90.com in US), the specters of yellow-card accumulation and injuries hang heavy in the air.

Concacaf has not included an accumulation reset, as is the norm in such tournaments to diminish the chances of players missing the final for innocuous reasons, meaning any two yellow cards will see a player suspended for the next match.

For TFC that list includes: Michael Bradley, Jozy Altidore, Sebastian Giovinco, Jonathan Osorio and Drew Moor. Should any be cautioned in the first leg, they will not be available for the decisive second because of a two bookings through seven matches.

In fact, Bradley has been carrying his since the opening match of TFC's run – a span of six matches. He was booked for time-wasting when the referee deemed he was taking too long to restart play on a free kick against the Colorado Rapids in February.

“It has to be an oversight,” said Greg Vanney via conference call on Thursday. “When they reorganized the event, maybe that wasn't something they looked closely into or at all.

“To be in Concacaf, the environment, the competitive level, the difference in referees and how they approach the game and everything else, it's very difficult to manage two cards over that many games. It's something they need to revisit. I don't think they're going to do it mid-tournament, so nothing can change now.”

His message to those facing the unthinkable: “We have to be smart.”

“What I say is, 'if you have to take a yellow card because it is necessary in the game, then that is part of the game. If you don't, don't. And absolutely, positively, don't take any stupid yellow cards, such as running your mouth, kicking balls away or anything like that.'

“They understand that,” added Vanney. “Somethings are unavoidable and others ... you have to stay out of those situations.”

In addition to those concerns, up to five potential starters were unavailable – Victor Vazquez, Chris Mavinga and Justin Morrow – or forced off prematurely – Altidore (foot/ankle) and Gregory van der Wiel (undisclosed) – in the second leg against Club América.

Vanney was optimistic that four of them would be ready for action come Tuesday.

“Chris is making progress,” said Vanney of Mavinga's abdominal discomfort. “He was not as far along as we wanted him to be to play in Mexico. With every week that passes we're getting closer. If he's progressing as we hope, and should, then he'll be available for Tuesday.”

Of Morrow, Vanney said: “Justin is doing well. He was close to playing this last match, but still had a little tenderness in the calf. He trained, we just couldn't afford to put him out there and have something go wrong.”

And as for van der Wiel and Altidore, who returned to Toronto from Mexico City, Vanney added: “With Greg, it's a management thing, tendonitis-type stuff. He should be fine. Jozy: all indications from him are that he should be fine and good to go.”

“It's been a difficult start of the season on guys physically,” said Vanney. “We've played on multiple different surfaces. The bodies are taking a bit of a grind.”

That leaves Vazquez a question mark.

“It's a precarious thing: a nerve issue in his back,” explained Vanney. “The indications from the specialist we talked to were it's a time issue. [There is not] anything more that anyone can do. We're taking steps slowly, but surely, continuing to try to make progress where we can. There's a typical window of time and we're right on the edge of it. We're not quite sure where [he] will be coming into Tuesday.”