Kagawa said that he is "irritated" by his performances this season and that he has to focus on improving in the second half of the season to prove that he has grown as a player, reports Sky Sports.

The midfielder has not scored any goals, and has only made nine Premier League appearances so far this season. Kagawa is not a first choice for manager David Moyes, and he is starting to show a bit of frustration that he hasn't reached the heights he did in Germany before moving to Manchester.

Kagawa's agent denied that Kagawa was likely to leave Manchester United as rumors of a move to Germany have heated up recently, reports Sky Sports.

In addition to speculation that Kagawa was on his way out of Manchester, the team is closing in on bringing Juan Mata in. Kagawa hasn't been as prolific in England as he was in Dortmund, but his agent believes the midfielder will stay put.

Kagawa is available off the bench for Manchester United's Capital One Cup match against Stoke City on Wednesday.

Kagawa had been suffering an illness over the past few weeks, including having to get his stomach pumped. While he isn't starting Wednesday's match, it wouldn't be surprising if he saw some action ahead of this weekend's tilt with West Ham.

Manchester United manager David Moyes said that Kagawa is still not feeling well after being taken to the hospital after being ill nearly two weeks ago, according to the Daily Mail.

Kagawa "ate too much" and had to have his stomach pumped two weeks ago, after United's loss to Everton. He did not play Sunday against Aston Villa, but was able to feature during the week in the Champions League. Kagawa is still working to recover from the incident.

Kagawa has returned to fitnessfollowing an illness that kept him out of last Saturday's loss to Newcastle.

Kagawa was held out after having to have his stomach pumped due to overeating. However, he's back in training and could very well be back in the starting XI in Tuesday's Champions League match against Shakhtar Donetsk.

Kawaga was held out of Saturday's 1-0 loss to Newcastle at Old Trafford due to an illness, ESPN FC reports. Manager David Moyes said "it was a bad sickness. He thinks he ate too much, and he had to get his stomach pumped, but I think he is okay."

Kagawa has started to get a little more time on the pitch lately but eating his way out of another appearance surely won't help him get more shots at the starting XI. His next opportunity to play comes December 10 against Shakhtar Donetsk before another Premier League match next Sunday against Aston Villa.

Kagawa could miss Saturday's match against Newcastle due to an illness, the Manchester Evening News reports. "Shinji has a sickness bug," manager David Moyes said. "We need to see how he is on Saturday but he wasn't too good after the game [Wednesday]."

With Wayne Rooney (suspension) and Robin van Persie (groin) both out Saturday, Kagawa would have been a big part of the United attack, although the illness is very much an issue this weekend. Even if he does play, it appears he won't be at 100 percent.