Manchester United have confirmed that the ankle injury Wayne Rooney sustained during Sunday's 2-2 draw at Bolton Wanderers is severe enough to stop the England international travelling to Spain for the Champions League clash with Valencia.
The former Everton star had to be substituted in the 61st minute at the Reebok Stadium.
Rooney joins veteran winger Ryan Giggs on the sidelines. The former Wales international has a hamstring problem and will be out of action for the next two weeks.
United opened their Group C campaign with a disappointing 0-0 draw against Rangers a fortnight ago while Valencia are currently top of La Liga and thrashed Bursaspor in their first group match.
Assistant manager Mike Phelan had played Rooney's injury down after Sunday's match, saying after the draw: "Wayne Rooney had a bit of a knock. He has a little issue with his ankle, we don't know how serious.
"We'll have a look in the morning but we think he'll be okay for Wednesday. He's been playing with it for a couple of weeks now and, during the game, we decided he wasn't getting into the areas we wanted and he wasn't getting chances, so we had to change it."