Anderson admits his injury nightmare at Manchester United has been hard to take.
To miss most of the club's unsuccessful league title defence last season was another crushing setback.
The Samba star told the Daily Star Sunday: "Last season was very sad for me.
"I had worked hard in pre-season and in the first five games I played very well and the team was doing very well.
"But then I started to feel my knee getting weak in the game with Chelsea. It was very painful and that's when I had to stop and come off.
"Afterwards, they found there was a 30 per cent difference between my left and right knee. That's why I couldn't play on. It was very sad but that's football."
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