Kevin Pietersen [Images] defended his decision not to walk early in his innings of 104 not out against Pakistan on the first day of the third Test on Friday.

Pietersen, whose key innings helped England [Images] to 347 for six, was given not out after apparently edging a ball from fast bowler Shahid Nazir via his leg to the wicketkeeper after making just two runs.

"I wasn't 100 percent sure I had nicked it. There was a mark on my trousers," he told a news conference. "I'm not out there to give decisions. I'm not sure I'm the only batsman in the world who doesn't walk."

Pietersen, who was also dismissed by a no-ball on 29 and then dropped just before retiring hurt, accepted that it might have been his lucky day "but you take the rough with the smooth. I got a bad decision in the first innings at Lord's when I was feeling pretty good. That's just life.

"I was really satisfied with this innings after getting 20s, 30s and 40s in my last three innings."

The 26-year-old had acupuncture on his left forearm after being forced off with cramp.

"My arm would just freeze," he said. "It wasn't fun, it's never happened before. But I will be facing the first ball on Saturday, unless something drastic happens.

"I had been due in next but Hoggy (Matthew Hoggard [Images], who was dismissed with the last ball of the day for a duck) went in as the nightwatchman.

"There's still quite a bit left in the wicket. I didn't feel once all day that I was really in on that wicket.

"We set ourselves the target of getting 400 or 400 plus in the first innings and hopefully we can do that."

England lead the four-match series 1-0. They have not beaten Pakistan in a home series since 1982. Ian Bell [Images] was 66 not out at the close.