Pakistan, who look certain to make it to the last four, have quite a few things dogging them at the moment but ball tampering allegations are tops.

Match referee John Reid of New Zealand reportedly had an unpleasant exchange of words with Pakistan manager Zafar Altaf at the end of that country's match against South Africa at Trent Bridge.

The ball used in South Africa's innings reportedly did not pass muster with the referee who had a word with Altaf on the matter. The Pakistan manager was upset and asked how come his team was being singled out for such allegations, reports said.

He is also said to have asked Reid to do whatever he must do. It was not immediately known whether Reid had asked for a thorough look at the used ball.

The feeling in the Pakistani camp is whenever they do well, they are accused of unfair practice andthis is yet another instance of putting pressure on their team. They also feel the current controversy will build up around the semi-final stage.

Meanwhile, teams playing Pakistan have started using a new strategy of asking for the ball to be replaced between the 40th and 45th over of an innings.

The Pakistanis are known experts of reverse swing and a new or `undoctored' ball is unlikely to swing as much as one which has been `worked on'.

Both Australia and South Africa employed the same tactics in their matches against Pakistan and succeeded in limiting the effectiveness of the Pakistan bowlers.

Another reason the Pakistani camp feels the ball is being changed at the 45-over mark is because the authorities want to retain the used ones for inspections, to be conducted later.

It is said they don't want to lose the ball in the crowd invasion and the evidence `destroyed'. Shoaib Akhtar -- the man aiming to break the 100-mile per hour (160 kph) barrier -- in particular, is reportedly under keenobservation as there is a feeling he `might have been tampering with the ball so far'.