London Welsh director of rugby Rowland Phillips has said that Chris Hala'ufia's red card had a "massive influence" on their loss to Leicester Tigers.
The Exiles led at half time as they continued to hunt for a first win of the season in the Aviva Premiership, but they slipped to a 38-17 defeat after Hala'ufia was sent off for two offences against Laurence Pearce.
Phillips told BBC Sport: "I did not see anything wrong with the tackle. The initial call was that it was 'no arms'.
"I don't know whether he was yellow-carded for what was deemed to be a 'no arms' tackle, or red-carded for pushing the guy on the floor. I can't comment on the reasoning, but it had a massive influence on the game."
Welsh have just two matches remaining to try to avoid finishing the campaign without a win.