MONTREAL -- The Montreal Impact may have an important weapon in their bid to reach the MLS Cup final -- the hard, unpredictable artificial turf at Olympic Stadium.

The Impact opted to move indoors for the opening leg of their two-game, aggregate goals Eastern Conference final against rival Toronto FC on Nov. 22 to avoid cold weather and draw a huge crowd.

A bonus is the synthetic pitch that is laid atop the concrete floor of the Big O, which has given some very good visiting teams fits in the past for its high bounces and uneven footing.

They will begin practising daily in the cavernous dome starting Thursday to get used to its bumps and nuances.

"There are certain areas where it's hard and there's concrete under, and certain areas are hollow," Montreal goalkeeper Evan Bush said this week. "I'm not sure if there are trap doors under there or what.

"Maybe (former Montreal Expo's baseball star) Moises Alou is hiding under a trap door under there, I don't know. But it's not only the bounce, but depending on whether they water it or not, it's how it skips off the (artificial) turf compared to grass. That's why it's important for us to be there five days before the game, to see all those little things again."

The Impact have upset some gifted teams there, including a rousing 2-0 win over Mexico's Santos Laguna in the 2009 CONCACAF Champions League quarter-finals. They got past Mexico's Pachuca and Costa Rica's Alajuelense in the same venue en route to the 2015 Champions League final, where the magic ran out with a 4-2 loss to Mexico's Club America on April 29, 2015.

In each case, the visitors struggled to adjust to the vast space in the dome, the large, deafening crowds and the unexpected bounces.

"It's important that we take advantage of seeing how the ball rolls there, because it is different," said Bush. "For goalkeepers in particular, seeing crosses and balls played over long spaces is different on a small field compared to a big stadium.

"All those little things that you might not think about too much, we have to take into account. We have to use it as an advantage."

Toronto's players feel they can adapt to playing on any synthetic surface.

"I was a little disappointed to see that we're going to be back on (artificial) turf but I think the positive is it sounds like it's going to be a great crowd and a big-time atmosphere," said TFC goalie Clint Irwin. "So we're excited about that.

"It doesn't really change too much for us. It's a different surface but we've played on (artificial) turf throughout the year. It's not that big of a deal."

TFC has a synthetic field at their training centre, but coach Greg Vanney knows his players aren't wild about using it.

And whatever happens in Montreal, TFC will be back on grass for the second leg on Nov. 30 at BMO Field.

"Usually these (artificial) turf fields are fast, they're bouncy," said Vanney. "The game has a hard time settling down sometimes just because the ball doesn't settle down.

"I personally have not played in Olympic Stadium or been involved in a game there so I don't know too much about it, only what people tell me. But it's a different type of game. We just have to be ready for anything that can happen. Ultimately, you just have to be switched on and ready for a game that could be high energy, again because the ball's going to be moving fast and the intensity will be there, no question."

The Impact normally play on a grass pitch at Saputo Stadium, but they use the Big O for games early in the season when it's snowy outside. Their first two regular season home games were in the dome in March and April, victories of 3-0 over the New York Red Bulls and 2-0 over Columbus.

They are expecting a crowd in the 60,000 range for the first conference final match for both Canadian franchises. The winner of the series advances to the MLS Cup final on Dec. 10.

"It's a tremendous atmosphere," said Montreal coach Mauro Biello. "You get 50,000 or 60,000 in there and it's like a plane is landing.

"For the players, it's big because when you make a nice play and you hear the crowd behind you it gives you confidence. For the surface, if you're able to train on it, you'll get more familiar with the bounce of the ball and it's an advantage against a team that is coming in fresh and has to deal with the crowd and with a field they're not accustomed to."

With files from Neil Davidson in Toronto