Zaheer Khan has suffered a hamstring strain, but the status of his availability for the rest of the first Test and the series remains unclear. Zaheer underwent an MRI scan and is unlikely to bowl in the remainder of England's first innings, though he has not yet been ruled out of the entire Test, according to the Indian team management.

It is understood that Zaheer was cramping in the dressing room after he limped off midway into the third over of his third spell. He was attended to by the Indian team physio, but team manager Anirudh Chaudhary did not confirm if Zaheer left the ground to undergo any scans. Meanwhile, Duncan Fletcher, the India coach, was also non-committal on how long Zaheer would be out for. "It was quite a loss for us at that stage as he could have got us that third wicket and even more the way he was bowling," he said.

Fletcher would have loved for that to happen as it would have been a nice way to celebrate his hundredth Test as coach of an international side. But he did not want to be drawn in by the media concern over Zaheer's injury and its possible impact on the match and the rest of the series. He would only say it would be wise to wait till tomorrow before talking about the future.

The injury was an unfortunate incident that is bound to affect the predictions for the series because till he went back to the dressing room Zaheer was simply unplayable. Everyone had anointed him India's lynchpin and his contests with Andrew Strauss, Alastair Cook, Jonathan Trott and Kevin Pietersen were the ones the full-house at Lord's sat quietly in anticipation of.

Zaheer did not disappoint. He came into the match on the back of going wicketless in a practice game against Somerset, followed by light training - stretching and conditioning mostly - sessions in the two days leading up to the Test match.

It would not be an overstatement to say Zaheer is currently the most complete seam bowler in the world. Dale Steyn might be at the top of the ICC's Test bowling rankings but he relies on uncompromising pace and away movement to trap his victims. Zaheer's skills are more varied: he can swing the new ball both ways, also cut the old ball both ways, and then cup the ball when it is roughed up on one side to reverse swing it. He does all that while using the crease and bowling from both over and around the wicket. The batsman never knows what Zaheer is thinking.

Just like bowlers stay away from engaging men like Sachin Tendulkar in verbal jousts, batsmen do not like engaging themselves in a duel with Zaheer. England would know that better than anybody after Zaheer flattened them at Trent Bridge on India's last tour in 2007, picking up nine wickets after being riled up by the jelly beans incident. Back then he had been England's bugbear, bowling unplayable lines from around the wicket to overwhelm them.

In his first spell of this tour he had both England's left-hand opening batsmen on a string. Cook had already been left guessing by Praveen Kumar, who started off with two exquisite deliveries that moved away from the left-hander. Zaheer's ploy was more complex: he drew Cook out by bowling outswingers and then suddenly darted one into him. He then caught Cook off guard with a delivery that straightened on leg stump.

Strauss was far from comfortable at the other end. Zaheer had understood that the surface was slow and he had to pitch the ball a little fuller. He teased Strauss with varied lengths, keeping the England captain vigilant. Interestingly, Zaheer kept a deep square leg in for Strauss throughout, but bowled only two bouncers. Strauss is usually very good at picking the right delivery to go after. But Zaheer's steepling bouncer in his second spell surprised him and he hurried into his pull, and was gone after having spent nearly two hours at the crease for just 22 runs.

With the last ball of the same over Zaheer nearly got Jonathan Trott to edge a delivery that shaped away from him. Zaheer appealed though he knew there was no contact. He just wanted to make sure Trott, who has been freakishly consistent since making his debut for England two years ago, was aware who was calling the shots on the day.

After lunch, Zaheer kept England under intense pressure; he bowled 5.3 overs without a run being scored off the bat. Trott and Kevin Pietersen had to endure tight lines and teasing lengths, and had to be careful they did not play too early or too late.

In his third spell Zaheer charged in from around the wicket, hiding the ball in his palm as he ran in. The first ball was bowled fuller, at Pietersen's toes. The next delivery he went wide of the crease and got good away movement. Pietersen chased and was lucky not to edge. For the last ball Zaheer changed to over the wicket. Pietersen did not move his feet and played a fuller, angled delivery from his crease. It was clear Zaheer had Pietersen worried.

Testing the batsman's patience is good but one of the most important virtues Zaheer possesses - one that is key to success in Test cricket - is patience. As Mike Atherton observed from the commentary box, Zaheer is never in a rush to get his men. He works them out in spells. He is willing to play the waiting game. Perhaps, he gets some sadistic pleasure out of playing with his catch, having already hooked the bait.

Fletcher can remain stone-faced, act unworried, but underneath even he knows that if India have to maintain their No. 1 Test ranking they need a fit Zaheer back.

Nagraj Gollapudi is an assistant editor at ESPNcricinfo