Lee Cattermole has said he felt he was not even 'half fit' as his injury problems worsened at the start of the season.
Cattermole made just three appearances during Sunderland's wretched start to the campaign, last appearing in the 3-2 defeat to Crystal Palace in September.
His injury was initially something of a mystery until it was diagnosed as a hip operation that required surgery.
The 29-year-old has now been training for three weeks 'without pains' and has told manager David Moyes that he is ready to return to the squad for the crucial away clash with Watford.
Cattermole told safc.com: "It’s been lingering on for a long time and I didn’t realise how much it was affecting me. When you’re trying to play and you’re not even half-fit you’re going to let your team-mates down.
“That was it for me – Crystal Palace at home. I was warming up and I thought I was doing myself such an injustice and it’s going to affect the team as well. That was when we started to look a bit deeper and made a decision.”
The influential midfielder suffered a setback during his recovery, requiring an injection in his ankle, but says he hopes that will eventually work to his advantage during the closing weeks of the campaign.
He said: “It’s been a long haul with lots of ups and downs along the way and I’ve had a little setback but I’ve tried to use it as a positive,
“I’ve had another four weeks in the gym which I wasn’t expecting but hopefully that will hold me in good stead in the weeks ahead. It was a big operation and there’s a lot of time off your feet so when you come back things are going to flare up and react. It was a bit frustrating but that’s behind me now and I’m feeling strong.
"I had a brief chat with the manager and told him mentally I was in a good place, I might have wanted a couple of reserve games but I don’t feel I need them. I just feel like it’s a good time to be in and around the squad and I’m ready to play my part."
Cattermole is known to be an influential presence in the Sunderland dressing room and his return will be a major boost to a squad struggling for form and confidence.
He opened up on his frustration at being stuck on the sidelines, saying: "You go home from training hearing whispers about things going on and I’ve gone to all the home games in the dressing room. You want to be in control of the job yourself but I’ve tried to help the boys as much as I can without adding pressure to the team. It’s trying to find that balance.”