Romelu Lukaku had a perfectly good reason for not celebrating Manchester derby victory

He didn't seem right.

As Paul Pogba and Alexis Sanchez came alive at the Etihad to stun Manchester City, Romelu Lukaku remained a strangely subdued figure. The Belgian striker had been in fine form leading up to the derby, scoring in three consecutive games against Swansea, Brighton and Sevilla. However, he looked out-of-sorts against the Premier League leaders, even when Pogba and Sanchez inspired a rousing United fightback, clinching a 3-2 win having been 2-0 down. https://twitter.com/AdamSMarshall/status/984526188382171137 As it turns out, Lukaku was very much feeling under the weather. According to Adam Marshall, who is a member of United's media team, the forward was unable to join in with the post-match celebrations because he was throwing up in the toilets. While that is slightly concerning to hear if you're a United supporter, thankfully Lukaku seems to be feeling much better, posting a selfie on Twitter after training on Friday morning. Not only that, he's going to unwind with a few games of NBA 2k 2018 on the Xbox before settling down for some shut-eye this afternoon. https://twitter.com/RomeluLukaku9/status/984812361927274496 It all points to Lukaku being relaxed and refreshed as he looks to get back among the goals on Sunday when he faces former side West Brom at Old Trafford. The Baggies are struggling, adrift at the foot of the Premier League table having sacked Alan Pardew earlier this month. Meanwhile, United boss Jose Mourinho has suggested that he would have to sell before buying a striker to compete with Lukaku. Recent reports have suggested that Anthony Martial is open to leaving in the summer after falling below Alexis Sanchez in the pecking order. Refusing to be drawn on the Frenchman's reported misgivings, Mourinho merely said that buying players to compete with Lukaku would mean further competition for other members of the squad. "I don't," Mourinho said when asked if he has plans to bring in another striker. "If I have more competition for him, I have more competition for the other ones and then they are not happy because they are not playing. So probably I would have to reduce and send some away."