THE former Lions and Ireland prop, Paul Wallace, has questioned Harlequins' use of blood substitutes during the London club's Heineken Cup quarter-final defeat by Leinster at the Stoop last Sunday.

Although the suspicious circumstances surrounding the re-introduction of Nick Evans in place of a supposedly bloodied Tom Williams in the 76th minute of the game are currently being investigated by the ERC, Wallace is convinced that Williams' 'injury' was not legitimate.

"I saw Tom Williams kneel down, and move his hand from his sock to his mouth before he came off. To my mind, this is a clear case, as there didn't appear to be any contact between Williams and anyone else," said Wallace who was working as an analyst at the game for Sky Sports.

There have been suggestions in the aftermath of the incident, which left thousands of TV viewers non-plussed, that the red liquid coming from Williams' mouth might actually have been vegetable dye. And there were more questions raised when the Harlequins player was clearly seen winking in the direction of Evans who was waiting to come on.

"I'm not qualified to know about things such as vegetable dye, but it didn't look like the colour of blood you get from a mouth injury. There was a little trickle, then it gushed out after he took a sup of water," added Wallace who also played for Leinster in the Heineken Cup.

Earlier, Evans had been replaced by Chris Malone in what Harlequins insisted was a tactical substitution although it was obvious that Evans was struggling with a knee injury. Malone was subsequently forced off with a hamstring pull and replaced by Williams, but with Leinster leading 6-5 going into the dying minutes, it seemed that Harlequins were desperate to get Evans back on the pitch in an effort to win the game either with a penalty or a drop goal.

Under Exception 1 of Law 3.12, a player who is tactically substituted, rather than replaced, is entitled to return to the field for blood reasons. Given that Evans was clearly injured, Harlequins were already bending the rules by sending him back on, however the Williams incident appears to be a more flagrant breach of the regulations.

The investigation is being carried out by ERC disciplinary officer, Roger O'Connor, who has already sent a number of questions regarding the incident to both Harlequins and Leinster. He will also be reviewing TV coverage of the game, and it is possible that some footage which was not seen during the live broadcast may shed more light on what happened.

In the meantime, Williams started at full-back for Harlequins in Friday's 28-6 English Premiership defeat at Sale.