The roles are reversed at this year's OUA semifinal, which is rematch of last year's Yates Cup.

When the McMaster Marauders faced off against the Western Mustangs for the Ontario University Athletics trophy in 2011, they did so after dropping a game to the Mustangs early in the regular season.

This time it's Western that is coming into the playoffs having been beaten by the Marauders in regular season play.

One would think an undefeated record could only mean good things — but according to head coach Stefan Ptaszek, McMaster's perfect season is causing him a bit of a worry.

"As a coach, it's very unnerving to not have that type of adversity in the regular season," Ptaszek said.

"You have to be more internally motivated and you have to push every week without an example in the regular season to say 'we're not there yet.'"

Ptaszek said he'll be leaning on the seniors on his squad, and guys like quarterback Kyle Quinlan, to see them through this tough game.

"There are a lot of nervous Marauders on this campus," Ptaszek said. "They don't always like the Mustangs, but they know they have to respect them and be careful."

The Marauders are coming off a perfect season, finishing at 8-0 with 16 points. Western is in fourth place in the OUA with a record of 5-3 and 10 points.

The Marauders beat the Mustangs 33-27 at their regular season matchup in September.

"I believe we have a good team this year," said Western coach Greg Marshall. "We've had some adversity, but that happens."

"We've got a good, competitive squad, and this is as big a road playoff game as we'll ever play."

The OUA semifinal takes place at Ron Joyce Stadium at McMaster University at 4:30 p.m. Saturday.