Johnny Sexton's first outing as Leinster captain lasted less than 10 minutes after he suffered a clash of heads with Wasps' former Leinster player Brendan Macken.
Leinster later confirmed that Sexton subsequently failed his Head Injury Assessment for suspected concussion, with Cathal Marsh taking over at outhalf.
The news will come as a big worry ahead of the start of the build-up to the Six Nations, although Sexton remained on the sideline of the Champions Cup game at the Ricoh Arena.
Sexton has suffered a catalogue of concussions in recent years and is now set to miss out on training as Joe Schmidt gathers his squad next week ahead of the opening game against Wales at the Aviva Stadium on Sunday February 7th.
There was further bad news later in the game when tighthead prop Marty Moore was helped from the field with a leg injury.