Ulster could be without John Cooney, Iain Henderson and Tom Stewart for Sunday's Heineken Champions Cup opener against Sale Sharks on Sunday.The province have confirmed that all three players are following the return to play protocols after brain injuries in Saturday's defeat to Leister at the RDS.The trio were removed from the field for head injuries during the game, with Stewart also needing treatment for a blood injury after the head clash which saw Leinster's Cian Healy red-carded.Cooney was replaced early in the second half following a nasty collision with James Lowe, while Henderson was removed shortly before the hour mark, after appearing unsteady on his feet.Sunday's opponents Sale will be well-rested, having had a week off in the Premiership last weekend.Alex Sanderson's side have been in fine form in the Premiership this season, with seven wins from their nine games leaving them second in the table.Ulster are in Pool B of the season's tournament, with Ronan O'Gara's La Rochelle their other opponents, welcoming the defending champions to Belfast on Saturday 17 December.Listen to live commentary of Sale Sharks v Ulster on Sunday on RTÉ Radio 1 Extra (from 1pm) and on RTÉ Radio 1 (from 2pm).