Manager Steve Lomas knows his St Johnstone side face a daunting task in their Scottish Communities League Cup quarter-final against a Celtic team riled by recent defeats.
Not only will Neil Lennon's men be eager for revenge against St Johnstone, who won 2-1 in the Clydesdale Bank Premier League last month, but they will also be determined to respond to Saturday's home loss to Kilmarnock.
"We're massive underdogs but we go there in good heart," Lomas told Press Association Sport.
"We've seen what Kilmarnock were able to achieve. Neil's been saying they want a response, so it's probably the worst time to play Celtic.
"They'll be wounded, they'll want to bounce back - it will make it tougher for us."
Prior to Saturday's loss to Killie, Celtic's only defeats this term were against St Johnstone and at Barcelona last Tuesday night.
Lomas downplayed the significance of his side's 2-1 win on September 15, a result which sparked a seven-match unbeaten run ahead of the trip to Parkhead.
"It's a totally different game," Lomas said.
"It's about who performs on the night. We're under no illusions it will be very, very difficult.
"We're really looking forward to it. The boys always enjoy playing at Celtic. We're going to go there, give it a right go, given the size of the task."
A week ago, Celtic were granted many plaudits for pushing Barcelona close in the Champions League, only for the Catalan club to claim a last-gasp victory.
Lomas, who came through the youth system at Manchester City with Lennon, was among those to wish Celtic well, sending his friend a text message.
Lomas added: "I just wished him good luck. In Barcelona I thought they played really well and were unfortunate not to get what would have been a great result.
"I'll see Neil on the night. We'll have a drink after the game win, lose or draw."
While Celtic were beaten by a late goal, St Johnstone recently benefited from one.
David Robertson's stoppage-time goal ensured the Perth men's undefeated streak continued at the weekend, but the point came at a cost.
Striker Gregory Tade, who scored the equalising goal at McDiarmid Park against Celtic before Rowan Vine struck the winner, had to go off with a blow to the leg.
"It's looking doubtful for Gregory," Lomas said.
Defender Frazer Wright was also forced off with a broken nose, adding to an injury list that for the Caley Thistle clash included Peter Pawlett (hamstring), Craig Beattie (thigh), Jamie Adams (back) and Paddy Cregg (hamstring).
"We've probably been getting away with a little bit of luck with injuries," Lomas said.
"For two Saturdays we only had 13 outfield players, so somewhere down the line you're going to come a cropper."