Yorkshire were facing a huge dilemma yesterday as they awaited medical opinion over how long their Australian all-rounder, Ian Harvey, can be expected to be sidelined with his hamstring injury.

Harvey was due a specialist diagnosis at some stage in the afternoon and Yorkshire need to know by first thing this morning at the latest the extent of the problem.

If it is felt that Harvey could be out for any length of time then Yorkshire are poised to sign their overseas replacement, Phil Jaques, for at least three weeks which is the minimum period allowed.

In that case Jaques will play in today's Championship match against Essex at Chelmsford alongside Darren Lehmann but if they hear that Harvey's injury should clear up over the next few days then Jaques will not be called upon.

Lehmann and Harvey both returned to England yesterday following their fortnight with Australia's one-day squad in Zimbabwe where they won all three matches but Harvey was still apparently carrying the hamstring strain he picked up before leaving Yorkshire.

"It is a difficult problem but one which we need to sort out fast," said director of cricket, David Byas.

"If Harvey is going to be out for two or three weeks it would mean him missing the Cheltenham and Gloucester Trophy quarter-final clash with Lancashire at Old Trafford on June 16 and in that case we need to be sure that we have Jaques registered and able to play for us.

"It is not only the C&G that is important to us and it is crucial that we field our strongest possible side in the next two Championship matches against Essex and Durham."

It was beginning to look last night as if Jaques would take over from Harvey but if the all-rounder is going to be absent for a long time then Yorkshire may wish to explore other options for later in the season.

Jaques, unsure of what his immediate future will bring, travelled with Yorkshire to Chelmsford yesterday and left-hander Andrew Gale also joined the party as cover for the Australian.

Yorkshire knew they were in for an intriguing match because as well as Darren Gough bursting at the seams to prove a point or two against his native county - who will have their own firepower in Chris Silverwood and Steve Kirby - there was also the prospect of two spinners being up against each other.

Essex have Pakistan's Danish Kaneria in their squad while Yorkshire have included their own leg spinner in 18-year-old Mark Lawson who will make his first team debut if selected.

Yorkshire are seeking the double over Essex, who provided them with their only Championship win so far in the opening match of the season, but their opponents have improved a lot since then and are confident of notching their first win of the campaign.

Yorkshire from: Wood, White, McGrath, Lehmann, Lumb, Jaques, Gale, Dawson, Guy, Silverwood, Kirby, Bresnan, Lawson.

l England's hopes of developing into a side capable of winning the next World Cup could depend on the growing emergence of fast bowler Steve Harmison as an effective force at both Test and one-day international level.

Nearly all of the world's leading one-day units can boast a seamer of some reputation - Australia have Glen McGrath, South Africa still feature Shaun Pollock while Chaminda Vaas remains an integral part of Sri Lanka's plans - capable of restricting the opposition at both ends of the innings.

Harmison is yet to reach those heights, but he has the stage during the forthcoming three weeks of competition in the NatWest Triangular series to prove that he can be as effective in the shortened format of the game as he has been over the last six months in Test cricket.

''I think playing in this form of cricket might even help me as a Test bowler,'' said Harmison.

''It happened to me last year when I played four of five one-day games for Durham and I think I improved as a bowler because of them.

''There are very similar disciplines to first class cricket. You have to try and keep it tight and put pressure on the batsman. I've learned that being too attacking can cause you to concede a lot of runs in one-day cricket."