Montanier's side will host Angers on Tuesday for a spot in the Coupe de France final, which will be held in Paris on May 3, and Rennes will have to deal with a weight of expectation, as they are the clear favourites.
The pressure will also be on Rennes as they have not claimed a top-line title since 1971 when they won the Coupe de France, while their last trophy was from when they were crowned Ligue 2 champions in 1983.
Second-tier Angers have had a dream run, having only eliminated one Ligue 1 club - Sochaux - on their way to the final four of the cup competition.
Rennes, who sit 14th in Ligue 1, defeated Lille in the quarter-finals and Valenciennes in the Round of 32, while they have made two cup finals in the past five years only to lose.
In 2009, Rennes lost to Breton rivals Guingamp in the Coupe de France final, while last year they were defeated by Saint-Etienne in the deciding match of the Coupe de la Ligue.
"There is a lot at stake. This club has had a slightly odd relationship with the Cup. We can feel the weight of expectation," Montanier said on Monday.
"We need to focus more on the game than what is at stake.
"We have gone through some difficult times. If at the start of the season we had been offered the chance to play a semi-final at home in front of our own fans we would have taken it straight away.
"Now we are there but the final hurdles are always the toughest ones to get over."
Rennes lost 1-0 to Monaco on Saturday in Ligue 1 but that was their first defeat in five matches in all competitions as Montanier attempts to drag them away from relegation.
The club from France's north-west have risen to 14th over the past month and face an Angers team that have stumbled since the start of March.
Angers have lost four of eight games with just two wins in that period, as they have slipped to sixth in Ligue 2, but Rennes captain Romain Danze has warned his team against underestimating their opposition.
"We are both wary and confident. We are at home to a Ligue 2 team but they are trying to win promotion to Ligue 1 and they are also at ease away from home," the 27-year-old defender said.
"There are plenty of examples to prove that it is not always an advantage. Last year we celebrated qualifying for the final and it was followed by a massive disappointment.
"I hope this time we will have something to celebrate after the final."
The winner of Rennes and Angers will face either Guingamp or Monaco in the final.
