Clermont's Parra to make surprise Quins comeback
France's scrum-half Morgan Parra speaks during a press conference in Marcoussis, south of Paris, on November 21, 2013
The France scrum-half had not been expected to return to action until the end of the month due to a knee injury suffered in late November.
Parra, 25, had ruptured his cruciate knee ligament and was expected to be out for between 10 and 12 weeks but he is now set to make his comeback after just seven weeks of absence.
It is welcome news for New Zealander Cotter, who saw third-choice scrum-half Thierry Lacrampe ruled out of the match in midweek due to a knee injury suffered against Toulouse on Sunday.
It would have left Ludovic Radosavljevic as Clermont's only fit scrum-half for the crunch Pool 4 clash that they cannot afford to lose, or risk being knocked off top spot.
"He is ready to start the match. He's been progressing quickly and we knew it would be possible (for him to play) this week or next week," said Cotter.
"As he's at 100 percent, he'll start. He has, of course, passed all the necessary tests, so for me, that's the green light.
"It's important to recover our playmaker, Morgan is very important to our system. After Thierry's injury last week, it's obviously a good thing."
Clermont lead Quins by three points in the group, with only the winners guaranteed to reach the European Cup quarter-finals.
The Vulcans end their pool campaign at home to Top 14 rivals Racing-Metro next week while Quins finish with a trip to Llanelli to face Scarlets.
The news will also be a boost for France ahead of the Six Nations which begin next month.
Parra, who is a key figure in the French set-up, not least for his kicking ability, was not included in a 30-man squad for a training camp due to begin on January 19.
But France coach Philippe Saint-Andre said he could come into the picture if others pull out.
"We've already given a list of 30 players and Morgan wasn't on it. But then again, we'll see if there are any injuries or withdrawals," Saint-Andre told AFP.
"From Sunday (January 26) we can recall seven players to Marcoussis (due to be released on January 22, thus reducing the total number to a match-day squad of 23 players) so we'll see.
"But for now we hope he concentrates on his Clermont performances."
Saint-Andre's comments suggest that although he may not be part of the pre-Six Nations training squad, Parra could yet be called up ahead of France's first match against England at the Stade de France on February 1.