Giteau seeks improved performance
Matt Giteau echoed Toulon team-mate Bryan Habana's sentiments that the reigning European champions will need to up their game in next month's Twickenham showdown against Clermont Auvergne.
Toulon and Clermont will contest the fifth all-French major European final on May 2, and semi-final evidence suggests Clermont should start as favourites.
Although Toulon claimed a five-point victory over Leinster and Clermont experienced a similarly-tense 13-9 success against Saracens, Giteau and company did not remotely hit the standards they normally reach.
Habana's extra-time try made the difference in Marseille, with Wales full-back Leigh Halfpenny kicking 20 points, and repelled a brave Leinster performance, but Clermont were far more impressive in seeing off Saracens 24 hours earlier.
"We made it difficult for ourselves," admitted Australian back Giteau after the 25-20 success.
"It wasn't one of our best games, but in big games like these, you have to find a way to win.
"It felt like we never really had control and we couldn't find any rhythm, but we showed massive character in defence, and that's what got us through.
"The ball was wet and neither side could play in their own half.
"We made points, but then we gave points away.
"It's great having a goal kicker like Leigh Halfpenny. You can never replace a player like Jonny Wilkinson, but it's good having Leigh.
"We have to learn from this, and we will really scrutinise the performance. We can't afford to put ourselves under pressure in the big games."
Leinster led for large periods of a game that ended 12-12 after 80 minutes, but turned in the blink of an eye with an interception by Habana after he collected Ian Madigan's loose pass.
Habana added: "If we want to be contenders to win the European title, we will have to go back to the drawing board. As a team, we are going to have to look really hard at ourselves after that performance.
"Our discipline needs to be better and we can't afford to make as many errors. Mentally, I think we turned up and thought it was going to be a walkover, but the game ended up being on a knife-edge."
"Now we have the chance to make it a special end to the season for players like Carl Hayman, Ali Williams and Bakkies Botha, who are retiring.
"We've got 80 minutes, or maybe 100, to try to put them into the history books as legends with a third successive European win."
For Leinster, it was a case of what might have been as their hopes of reaching a fourth European final in seven seasons fell agonisingly short.
"The overwhelming emotion is one of pride," Leinster head coach Matt O'Connor said. "The effort the lads put in was fantastic and we are obviously incredibly disappointed to come second.
"Habana's intercept was the turning point - he is world-class - but the positive for us was the effort. It was second to none.
"A lot of people had written us off coming into this game, but we will back ourselves to go anywhere and beat anybody."
Saracens' exit in St Etienne ended English interest in this season's Champions Cup, and they must now swiftly turn to domestic matters, with Aviva Premiership leaders Northampton next up in five days' time.
Saracens remain on course for a home play-off tie, and their England number eight Billy Vunipola said: "We have still got very important games coming up, and we will move on.
"As the team is growing, we are learning to move on from disappointments, and one day we will get over the line."
Leinster announced on Monday that wing Fergus McFadden faces up to eight weeks out of action after breaking his right thumb during the second half against Toulon.
McFadden will miss the rest of Leinster's season, and he is due to undergo surgery on Wednesday morning.
McFadden apart, Leinster reported no other "significant issue" involving the remainder of their matchday 23 on duty in Marseille.
But Australia lock Kane Douglas, who did not feature at Stade Velodrome, faces a back operation on Thursday and could be sidelined for three months.