It's been a couple of days since he learned, to his considerable disappointment, that he hadn't been picked for India's tour to Sri Lanka, but Zaheer Khan has moved on. He is enjoying his stint with Worcestershire, who are trying to fight their way back into the first division of the English County Championship. There is a spring in his step as he speeds in to bowl against Gloucestershire at the picturesque New Road ground. After almost every delivery his team-mates, and the few hundred Worcester faithful who have turned up, do their bit to urge on "Zippy Zakky", the man who has been at the heart of their revival this season.

Zaheer has been nothing short of sensational, with 59 wickets from ten games. But how much can one really read into these numbers? After all, he has rarely failed to deliver in first-class cricket. Sidelined from the national side last season, he forced his way back for India's tour to Pakistan, having taken 43 wickets in six matches in the Duleep and Ranji trophies. It is believed that that comeback had the backing of Rahul Dravid.

But once in Pakistan, Zaheer looked a spent force - even if you account for the tar-road that masqueraded for a cricket pitch at Faisalabad. He looked out of shape, failed to sustain himself over long spells, and failed to impress on the seamer-friendly pitch at Karachi, prompting one insider to remark: "Zaheer is finished as a Test bowler; the earlier we accept it, the better."

Since then, he's missed the home series against England and the tour to the Caribbean, as the Indian team management have zealously invested in youth. Even though Irfan Pathan looked worn out in the West Indies, Sreesanth and Munaf Patel were impressive with the new ball. All things being equal, Zaheer's attitude towards fitness, which once led Bruce Reid, then India's bowling coach, to describe him as "mentally lazy", is likely to be a factor.

His fitness happens to be the one thing Zaheer has worked on since he came to England. He has shed weight and looks in top shape. His run to the wicket, which was a ponderous forward motion, now has a zip to it.

"It was one of the main reasons why I came here," he says. "I've been bowling a lot of overs [an average of 20 overs per innings] and that's helped in picking up my fitness levels. It's added to my confidence as well, and I'm very happy with the rhythm."

Vikram Solanki, Zaheer's captain at Worcestershire, has had no reason to complain. "He was very keen on improving his fitness when he came here. He's benefited from being here, since he's got access to all the facilities, with trainers, physios and masseurs at his beck and call."

Understandably Zaheer isn't going flat out while bowling, and has chosen mostly to rely on guile over speed. "There's more pressure at the international level," he explains, going on to add that the preparation and technique remain the same however. "The weather here is a big factor," he says looking up at the leaden skies. "The pitches you get here are totally different from India. There you rely a lot more on getting the ball to reverse. Here the conditions are more helpful; the ball does more if it's overcast."

Most of his team-mates at Worcester can't believe he's still with them. He's miles ahead of the rest in the second division - medium-pacer Jon Lewis was second in the table with 42 wickets. This season no other fast bowler, in either division, has managed five five-wicket hauls like Zaheer has.

In fact, one of those performances was a nine-wicket bag against Essex, where a dropped catch cost him a perfect ten. Solanki who has been with Worcestershire for over a decade has no hesitation in ranking Zaheer as "one of the best overseas pros we've had here". Ben Smith, one of the county's middle-order batsmen has been on the circuit for 17 years. He goes a step further: "I haven't played alongside a better bowler."

Zaheer has adapted to the conditions with remarkable ease. "He's added a little more to his game," says Solanki, who first got a look at Zaheer during his debut ODI series in Nairobi in 2000. "He works out situations when he can't run through the batting line-up and bowls tight spells, holds an end up, and works hard to get his wickets on placid pitches. The best part is, he's a strike bowler by nature and has the ability to take wickets in succession and change the course of the game."

Through our chat Zaheer regularly drops the word "performance". He's disheartened at being overlooked but insists it's something that spurs him on. "I was very disappointed not to be picked for the England series, but I've left that behind. That's why I've decided to come here and perform. My answer to everything is performance. I've decided to just keep performing. I was expecting a recall for the Sri Lanka series but things didn't happen. You just have to be patient. The good thing is, I have more matches here to stay in touch. The Champions Trophy and the South Africa tour are two big series that I am gearing up for."

For Worcestershire, he's been a breath of fresh air after the turbulence of Shoaib Akhtar last season. Shoaib, if one were to believe seasoned observers, was possibly the most unpopular overseas pro ever at New Road, and that had an impact on flagging team spirit as well. Zaheer has been different.

"What has been a real asset is that he's made himself so accessible to the boys," Solanki says. "He's spoken a number of times to all about aspects of reverse swing, how to disguise it, how effective it can be.

"I've played with some very fine overseas players like Glenn McGrath, Tom Moody, Andy Bichel, Kenneth Benjamin, Chaminda Vaas, but I would not be speaking out of turn if I say that Zak ranks right on top. He comes as an ambassador, and the way he goes about what he does is a sure reflection of an Indian Test player. He hasn't let himself down."

In October, Zaheer turns 28. It's a tricky time for a fast bowler who's at the top of his game but realises that his body may give way in a few years' time. It's tougher still because he's unsure about his place in the side, and his confidence has taken a few jabs along the way. At the turn of the century he represented a new era in Indian cricket, in the company of the new captain Sourav Ganguly, Virender Sehwag, and Yuvraj Singh: brash, aggressive and capable of delivering magic moments. Six years on, he's calmer and more mellow, waiting for one more chance.