Racing Metro (9) 19
Tries: penalty Cons: Wisniewski (1) Pen: Wisniewski (3) Drop-goal: Wisniewski (1)
Wasps (10) 17
Try: Varndell (2) Con: Cipriani (2) Pen: Cipriani (1)
Varndell scored two tries in a narrow defeat
Wasps must wait to find out if they have missed out on a home quarter-final in the European Challenge Cup after a last-gasp loss to Racing Metro.
The Londoners looked on course for victory until Jonathan Wisniewski's injury-time penalty won it for Racing.
Wasps were leading 17-16 thanks to two Tom Varndell tries and seven points from the boot of Danny Cipriani.
They had recovered from the sin-binning of Dan Ward-Smith and a penalty try but indiscipline at the end proved costly.
Wasps went to Paris unbeaten in the Challenge Cup and looking for victory to finish top of Pool Four, which would have ensured a home quarter-final draw.
But the Premiership side must now wait for the weekend to unfold before learning of their fate as the defeat means Connacht could finish as top seeds with victory at Olympus Rugby in Madrid.
It all looked good for Wasps until a high tackle on Wisniewski allowed the Racing fly-half to seal victory with the last kick of the game.
An opportunistic Varndell try and a Cipriani penalty had put the visitors 10-3 ahead in the 12th minute.
However, fly-half Cipriani then missed two further penalties before Wisniewski clawed the home side back to within a point with a penalty and a long-range drop goal.
Sustained Racing pressure led to Ward-Smith's yellow card in the 55th minute for killing the ball, and referee James Jones had no option but to award a penalty try for the home side as Racing took control of the scrum.
Despite their man disadvantage, Wasps hit back with Cipriani's adventurous long pass creating space for Varndell to dive over in the corner for what looked like being the winning score.
Racing Metro 92: Ward, Scarbrough, Masi, Steyn, Vakaloa, Wisniewski, Berry, Baiocco, Noirot, Smith, Dellape, Nallet, Leo'o, Culine, Chabal.
Replacements: Chavancy for Vakaloa (60), Fillol for Berry (57), Merabet for Baiocco (67), Diomande for Noirot (62), Tuugahala for Smith (46), Raiwalui for Dellape (40), Cronje for Nallet (66), Le Roux for Culine (49).
Wasps: Van Gisbergen, Varndell, Jacobs, Waldouck, Lemi, Cipriani, Honeyben, Payne, Webber, Broster, Veale, Skivington, Hart, Betsen, Ward-Smith.
Replacements: Matthews for Betsen (71). Not Used: Ward, Lindsay, Baker, Leo, Fury, Walder, Kefu.
Sin Bin: Ward-Smith (57).