Yasir Arafat will become a Sussex player next week - and he might not have to wait long for his debut.

Sussex have secured his release from his contract with Scottish club Clydesdale and are awaiting confirmation from the Pakistan Cricket Board that he will not be required for their A tour of Australia later this month.

The 24-year-old, who has been training with his new team-mates this week, will play for the second team against Yorkshire at Hove on Tuesday.

And his debut could be sooner than expected after Rana Naved, the player he is replacing, limped out of the Championship match against Middlesex at Horsham yesterday with a groin strain.

Rana went off after taking his 34th wicket of the season and is unlikely to bowl in the second innings. Sussex hope he will recover in time for next week's match against Lancashire at Liverpool but there is also the possibility that Pakistan may want him to rest the injury with their tour of England less than three weeks away.

Cricket manager Mark Robinson said: "We don't envisage any problem getting his release from Pakistan A.

"Three months in county cricket will develop his game, hopefully in the same way that Rana has.

"He's got a yard of pace, is quite skiddy and looks organised as a batsman. We also think he will fit in well in our dressing room."

Sussex are in a good position to strengthen their position at the top of the Championship after they dismissed Middlesex for 266 on the second day to gain a first innings lead of 110 which they had built on by the close by reaching 112-1 in their second innings.

Although Rana's contribution was, for once, negligible, it was no surprise that Mushtaq Ahmed was at the heart of things again.

The leg spinner took 4-92, bowling unchanged for 29 overs either side of lunch and his duel with Owais Shah, who held the reply together with a superb 126, was the highlight of a thoroughly entertaining second day.

At times it looked as if Shah was playing a different game to his team-mates. He certainly had as good a plan against Mushtaq as any batsmen this season, opening up his stance and clearing his front leg out of the way so he could work him into the gaps and put away any bad balls.

If Shah was watchful against Mushtaq he showed scant respect for Sussex's seamers, including Rana, as he raced to his hundred off 149 balls.

He dominated a secondwicket stand of 116 in 25 overs with Ed Joyce and when Middlesex reached 192-3 in mid-afternoon they were in a useful position.

But Shah went off for six overs to get treatment for cramps in his left hand - the same problem which forced him to retire during his maiden Test innings against India in March when he scored 88.

Shah would have preferred to have stayed off for more treatment but had to return only six overs later after Mushtaq had taken two wickets in three balls and Luke Wright, filling in admirably at the other end for Rana, had added to Joyce's wicket by removing Johann Louw.

Mushtaq finally got his man when Shah holed out to long-on shortly after resuming his innings but he had played a full part in an outstanding duel. He hit 15 fours and four sixes and lodged his 10,000th first-class run when he reached 103.

The contribution the ever-willing Wright made should not be overlooked either. He took 3-33 in a ten over spell which also included the wicket of Chad Keegan who was eighth out having an awful mow across the line.

Chris Silverwood belted a few boundaries at the end but the last eight Middlesex wickets fell for 78 and in just over an hour Sussex had shown why they are currently the best side in the country.

They strengthened their position after tea when Richard Montgomerie and Murray Goodwin took full toll of some wayward bowling after Keegan, easily the pick of the Middlesex attack, had Carl Hopkinson caught behind as he pushed forward in the third over.

Goodwin, in particular, relished the fact that Middlesex continually fed his strong areas outside off stump as he cut and drove his way to his second half-century of the match. Montgomerie looked tentative early on and was dropped at the wicket off Silverwood with just a single to his name.

But he grew in confidence and by the close had made his highest score of the season with power to add today.

Sussex start day three with a lead of 212 and their aim will be to bat Middlesex totally out of the game before unleashing Mushtaq.