Bath will join fellow English clubs Northampton and London Irish in facing an uphill struggle to progress from the tournament's pool phase if they suffer a second successive defeat.
While Bath were left to reflect on a five-point loss against Glasgow last weekend, Montpellier made an impressive Heineken Cup debut by holding reigning European champions Leinster to a 16-16 draw in France.
"Having Montpellier at the Rec is not just a challenge but an exciting event for us," Bath coaching chief McGeechan said. "The French don't have bad forward packs and they have the ability naturally to play fluid rugby. It is important we match that and put them under a bit of pressure.
"We know we've got to have our game spot-on."
Bath were outscored 2-0 on tries by Glasgow, and that failure to cross the opposition line cost them dear.
"We didn't do a lot wrong in the first 30 minutes except hang onto the ball a little too long in situations which could have led to tries," McGeechan added.
"When we were going well we didn't quite cross the line. We kicked penalties and three, six, nine points is okay, but five, seven, 14 or 21 is even better."
New Zealand World Cup winner Stephen Donald makes his first start in the Bath number 10 shirt, while former England captain Lewis Moody also features and Olly Barkley starts a comeback on the bench eight months after breaking his leg.
Montpellier skipper Fulgence Ouedraogo believes his team took a lot from the Leinster encounter, despite missing out on a win when fly-half Jonathan Sexton landed an equalising penalty strike with the game's final kick.
"Now we realise the difference between a champion club used to those big games and ourselves, who still need to learn," he said.
"It comes down to the small details that they master. They have a bigger intensity in the way they play and they maintain that pace until the very end. Perhaps we are guilty of having relaxed too early.
"Against a team like Leinster you pay a hefty price for not being thorough.
"They didn't flinch at any point and they played at full speed all the time. They even increased the rate towards the end, and it was hard for us to stay with them.
"But our young team managed to stand up to them and measure up to their players, and we will have to build on that performance.
"Our ambitions are definitely there, and when you are given the opportunity to compete in the Heineken Cup you really want to do well in it.
"Nobody wants to let go during this fierce competition. All the points are so precious, and we want our club to develop and enjoy a new boom."
Elsewhere on Sunday, Leinster host Glasgow, while Wasps continue their campaign in the second-tier Amlin Challenge Cup by tackling Italian side Rovigo at Adams Park.
Wasps, buoyed by a bonus-point victory over Bordeaux-Begles in France last weekend, should add another maximum to their Pool Three collection by sending Rovigo packing.
The group already appears likely to be decided by home and away meetings between Wasps and Bayonne next month, with both sides currently unbeaten.
"The aim is now to build on that performance (against Bordeaux), and we have to try to get maximum points at home," Wasps rugby director David Young said.
"The games against Bayonne could well decide the group - they have a pretty powerful side - but all we have been concentrating on this week is Rovigo."
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