Sidebottom (calf) and Starc (international commitments) will miss the next two County Championship matches away to Hampshire (July 11-14) and Derbyshire (July 18-21), prompting Yorkshire to scour the world for a possible alternative.
The club have revealed they did have one player in mind but the deal fell through. Martyn Moxon, Yorkshire’s director of cricket, commented: “With Ryan and Mitch both unavailable later this month, we are looking at the possibility of signing a pace bowler.
“We did have an overseas player in mind but, unfortunately, it came to nothing.
“At the moment, we’ve got nothing definite but we are continuing to explore the various possibilities.
“It’s probably more unlikely than likely if I’m perfectly honest, but we could possibly decide to sign someone on loan.”
Yorkshire’s efforts to recruit a replacement further demonstrates their commitment to winning Championship promotion.
The club are well-placed to achieve that target going into the second half of the season, lying third in the table, level on points with second-placed Kent and 32 points behind leaders Derbyshire with a game in hand.
Sidebottom’s injured right calf has kept him out of the last two Twenty20 games and, in a worst-case scenario, will rule him out of up to four Championship fixtures.
Starc, meanwhile, joins up with the Australia A squad in England ahead of the tour that runs from July 27 to August 14 after Yorkshire’s final Twenty20 group match against Derbyshire at Headingley Carnegie on Sunday.
However, Moxon has revealed that Starc will be back for the CB40 game against the same opponents at Chesterfield on July 22 and could also be available for the Championship fixture against Leicestershire at Grace Road (July 27-30).
He also confirmed Yorkshire will have Starc and Twenty20 overseas specialist David Miller available for a possible Twenty20 quarter-final on July 24 or July 25 but only Miller, at this stage, for a potential Finals Day appearance at Cardiff on August 25, even though Miller will also be on tour around that time with South Africa A in Ireland.
However, if Yorkshire reach Finals Day, they will talk again with Cricket Australia regarding Starc’s availability.
If Yorkshire are unsuccessful in attempts to recruit a replacement pace bowler, they would not seek to recall Ajmal Shahzad from his loan spell with Lancashire.
Nor would they call-up 23-year-pace bowler Oliver Hannon-Dalby, who has been made available for loan.
“Ollie has got to prove himself again and it would be good for him to go and get some first-team cricket under his belt,” said Moxon.
“He had a decent season in 2010 and then things did not go quite as well last year, but he’s a young bowler who’s still learning his trade and we just feel a loan move would aid his development.”