PARIS (AFP) - Lens will face fellow relegation candidates Paris Saint Germain in the French League Cup final after they won an astonishing semi-final 5-4 over Le Mans on Wednesday.

It will be a rematch of the 1998 final which PSG won.

Lens, coached by former French striking great Jean-Pierre Papin, had to come from behind twice to take what looked like an unassailable 4-2 lead in the second-half only for Le Mans to strike twice in a minute to level it.

However, Lens, who like PSG are former French champions but in distinct danger of being relegated, grabbed the winner a minute from the end of extra-time through Malien midfielder Sidi Keita - a remarkable return after he had been taken ill during a match and sent to hospital only 10 days ago.

Papin, whose side are just a place above the relegation zone only on goal difference, breathed a huge sigh of relief.

"That was a completely mad match, which you get occasionally in football," said the former Marseille and AC Milan marksman, who guided Strasbourg to the First Division last term and then replaced Guy Roux at Lens after only a few weeks of this campaign.

"The cherry on the cake is that this is the match we needed and the club showed real soul."

PSG had been the first to book their place at the March 29 final at the Stade de France when they gained a much needed morale boost to their traumatic season on Tuesday thanks to a 3-2 victory over Auxerre.

However the match featured yet another alarming mistake by PSG's France 'keeper Mickael Landreau, who punched the ball into his own net to let Auxerre back into the match at 2-1.

Landreau's error comes hot on the heels of two costly errors in the last two league matches which sees PSG lie only three points above the relegation places.

"That gives us a new dimension and new hope," said PSG coach Paul Le Guen, who has adopted a low key approach and allowed club president Alain Cayzac to do most of the explaining and excuses which the latter admits he finds tiring.

"However, given the league position we have to move on but at least this is a win we can enjoy.

"With regards to Landreau, he will be in goal for the next match (on Sunday away to second-placed Bordeaux) and I hope he doesn't make a fourth error."

PSG looked to have wrapped the tie up after the first-half with headers by Colombian international defender Mario Yepes and former Portuguese marksman Pauleta putting them 2-0 up.

However, Landreau's error rattled PSG's fragile nerves, which were settled once again with a shot by their longest serving player Bernard Mendy, whose 78th minute effort went through the Auxerre 'keeper's Remy Riou's legs.

Auxerre, who themselves have relegation worries being just seven points off the drop, managed to grab a consolation effort three minutes into time added on as Julien Quercia - who had only just come on as a substitute - shot home.