James Haskell is in danger of missing the start of England's 6 Nations title defence after being sent off in Wasps' dramatic 33-28 Champions Cup defeat by Harlequins.
Haskell was shown a red card by referee Roman Poite in the 75th minute for a shoulder-led high tackle on Jamie Roberts and in his absence James Chisholm crossed for the try that settled a remarkable clash at Twickenham Stoop.
Roberts' afternoon was over as the groggy Wales centre departed for a head injury assessment, although he left the pitch with an apology from Haskell that the veteran flanker repeated on Twitter shortly after the match.
"Whats done is done, but just want to publicly apologise to @Jamiehuwroberts," Haskell tweeted.
Whats done is done, but just want to publicly apologise to @Jamiehuwroberts. Never my intention to hurt another player. Got my height wrong, paid the price, which happens. You know me, never one to do anything subtly. Credit to @Harlequins and apologies to @WaspsRugby fans— James Haskell (@jameshaskell) January 13, 2018
"Never my intention to hurt another player. Got my height wrong, paid the price, which happens. You know me, never one to do anything subtly. Credit to @Harlequins and apologies to @WaspsRugby fans."
England open their Six Nations against Italy on February 4 knowing Haskell faces a ban for an offence that appears to be in the mid-range of making a dangerous tackle, which would result in a six-week suspension.
The flanker has just been restored to Eddie Jones' extended squad after emerging from a spell of bad form and would have been in the champions' plans for Rome and beyond.
"I'm not doing an Arsene Wenger, I haven't had time to really look at the tackle, but if it's a shoulder to the face or head he will get banned. You can't hide away from that," Wasps director of rugby Dai Young said.
"There was certainly no intent, he just tried to get off the line to shut the pass down. There wasn't much wrong with the timing.
"It's where the shoulder makes contact and that will determine whether he gets banned or for how long."
Young hopes that Haskell's strong disciplinary record - he has been banned for a total of five weeks for a head-butting incident in 2008 and punching in 2012 - will count in his favour.
"His track record should go in his favour, but only time will tell. James is really disappointed. He stood up and apologised to the player straight away," Young said.
Wasps led 21-0 and having let Quins back into the match, they secured the bonus point as they moved out of sight once more only to endure an alarming late collapse.
They can still qualify mathematically, but this defeat all but ended their chances of progressing when they enter their final group match against Ulster on Sunday.
"I think it's over for us now. I said we had to win both of these last two games and probably needed nine points. Two points here isn't enough," Young said.
"We'll want to win against Ulster and if a miracle happens then happy days, but miracles don't tend to happen too much in Coventry."
Quins' injury problems deteriorated further after England full-back Mike Brown sustained an eye problem.
"Mike's got a bang on the eye so he was reporting slight blurred vision so we just wanted to make sure he's alright with that. He's gone to get a check-up," Quins director of rugby John Kingston said.