Manchester United midfielder Ander Herrera is reportedly a major doubt for Sunday's Premier League clash with Chelsea at Old Trafford.
The Spaniard was forced off at half time during his side's 2-2 draw away to West Bromwich Albion on Monday night.
The 25-year-old aggravated the rib injury that recently kept him out of action for three weeks, according to Goal.com.
Herrera has scored two goals in five games for the Red Devils following his £29m summer move from Athletic Bilbao.
Monday's draw at The Hawthorns has left United in sixth place in the Premier League table with 12 points from their opening eight matches of the campaign.