Lloris was unconscious, says Villas-Boas
The Frenchman was caught by Lukaku's knee as he raced out to deny the Belgian striker a chance to break the deadlock late on.
After lying motionless for several seconds, Lloris was helped to his feet and looked set to be replaced by Brad Friedel, only for the 26-year-old to insist that he remain on the pitch.
"Hugo still doesn't remember the incident with Lukaku so he lost consciousness there, but he seemed assertive and determined to continue and showed great character and personality," Tottenham manager Andre Villas-Boas told BBC Sport .
"We decided to keep him on based on that.
"You see the player is focused and driven. It was a big knock but he looked composed and ready to continue on. The call always belongs to me.
"Brad was ready to come in but the person Hugo is there were enough signs for him to continue."
The visitors climbed to fourth with the point but would have gone second with a victory.
Lloris has kept 11 clean sheets in 14 matches for Tottenham this season.