New Zealand captain Stephen Fleming and Indian left-hander Yuvraj Singh will both play their last matches for Yorkshire next Sunday in the National League game against Surrey Lions at Headingley.
The pair will then head home for training camps in preparation for the Test series between the two countries in India next month, which is followed by a one-day triangular tournament.
Yorkshire's director of cricket, Geoff Cope, is currently searching for either one or two overseas replacements to help gain promotion to Division One of the Championship and avoid relegation in the National League. Yorkshire have three Championship games and three National League fixtures in September and the pressure is on to win all of them if the season is not to fizzle out.
"I am finding out firstly who is available and then who is most suited to our particular needs," said Cope.
"I will take my recommendations to the Management Board for approval and then arrange for visas, but everything will have to be done very quickly over the next few days."
With Yorkshire expecting to have a full battery of fast bowlers available for the climax of the season it is expected that Cope will try to sign at least one batsman to fill the hole created by the departure of Fleming and Yuvraj.
Whoever is signed will be a short-term measure because Yorkshire's needs will be different next season when the free-scoring Darren Lehmann returns, making another top batsman less essential than an all-rounder.
Neither Craig White nor Gavin Hamilton has been able to bowl this season and with the situation likely to remain unchanged next year, it is important that Yorkshire get an experienced all-rounder on their books.
Fleming was always going to miss September with Yorkshire, but the departure of Yuvraj Singh is something of a surprise because he was understood to be available all season when signed as a replacement for Matthew Elliott.
Matthew Hoggard and Darren Gough are both poised to make their comebacks tomorrow.
It will be Gough's first appearance for Yorkshire since announcing his retirement from the Test arena and Hoggard's first outing since an operation followed the cartilage injury which he sustained in the Cheltenham and Gloucester Trophy match at Worcester on May 28.
Hoggard, who has had two second team games recently, has been working out with the England bowlers at Headingley this week but he acknowledges that it is now too late for him to win back his Test place this summer.
Gough last turned out for Yorkshire when they conceded the double to Durham at Riverside on July 18. He then played in the first two Tests against South Africa before saying his knee would no longer stand up to the rigours of five-day cricket and his return for Yorkshire was then delayed while he had further rehab treatment and an injection.
Gough bowled eight overs in Yorkshire's match against the Bradford League on Tuesday, but he has yet to show he is strong enough for regular county cricket.
If he comes through Sunday's game without any problems, Gough should play in the Championship match at Colwyn Bay, which starts the following day. But Yorkshire may decide that Hoggard needs longer to build up his strength so that he is firing on all cylinders for the last three games of the season in September.
The only front-line seamer missing on Sunday will be Ryan Sidebottom, who twisted his ankle at Scarborough almost a month ago. Craig White misses the game because he is still suffering from the back spasms which kept him out of last Sunday's clash with Worcestershire Royals at Scarborough.
Yorkshire Phoenix from: Wood, Fleming, McGrath, Lumb, Yuvraj, Blakey, Gray, Dawson, Gough, Hoggard, Kirby, Bresnan, Silverwood.
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