Out of Sinc
The West Ham winger, by his own admission, produced a "nightmare" performance during the 1-1 draw with South Korea, when coming on as a second half substitute.
Injured Newcastle star Kieron Dyer has instead got the nod for the final slot in Sven Goran Eriksson's World Cup squad, although Sinclair remains on stand-by in case the Magpies midfielder does not prove his fitness before the World Cup gets underway next week.
"I've not been in the squad and, sometimes, I didn't feel part of the group," conceded Sinclair.
"Although the lads were brilliant with me, I just wanted to know if I was in the squad or not.
"It was a bonus getting a game against South Korea, but I gave the ball away a lot.
"It played on my mind being on stand-by.
"I had a nightmare didn't I?"
The 29-year-old still has an outside chance of appearing in the finals, but has returned home to train with his club West Ham.