Northern Ireland pair Keith Gillespie and George McCartney are set to start against Slovakia in Saturday's World Cup qualifying opener in Bratislava.
Gillespie has recently recovered from an ankle injury while McCartney has been overcoming a bout of pneumonia.
Both players missed the recent friendly against Scotland but are now match fit.
The withdrawal of Kyle Lafferty with a back injury means Warren Feeney is now the likely candidate to partner David Healy in attack.
Northern Ireland appear to have no further injury worries following Lafferty's withdrawal.
Lafferty pulled out of the squad on Tuesday but may return for Wednesday's clash against the Czech Republic.
The Northern Ireland squad arrived in Bratislava on Wednesday.
Previous fitness doubt Jonny Evans trained with the other members of the squad without any apparent ill-effects.
Rangers striker Lafferty joined up with the squad on Tuesday but was unable to train because of his back problem and returned to his club.
Northern Ireland boss Nigel Worthington will keep in touch with Rangers manager Walter Smith to monitor the player's fitness.
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Worthington is not optimistic about Lafferty's chances of facing the Czechs at Windsor Park on 10 September but is likely to give him every chance to prove his fitness.
The absence of the former Burnley frontman leaves the Northern Ireland manager with a squad of 21 for Saturday's opening fixture.
McCartney, Gillespie and Aaron Hughes are all back in the squad after missing the friendly in Scotland.
Partick Thistle goalkeeper Jonathan Tuffey has earned a first call-up.
Roy Carroll is an absentee from the squad after indicating earlier this summer that he would not travel to games unless he was guaranteed to start.
Therefore, U21 international Tuffey will join regular number one Maik Taylor and Linfield's Alan Mannus on the plane to Slovakia.
Ryan McGivern retains his place in the squad after his late-up for the game in Scotland.
McGivern is available for the 6 September game as his sending-off against the Scots was in a friendly fixture.
Northern Ireland squad:
Goalkeepers: M Taylor (Birmingham City), A Mannus (Linfield), J Tuffey (Partick Thistle).
Defenders: C Baird (Fulham), S Craigan (Motherwell), G McAuley (Ipswich Town), J Evans (Manchester United), M Duff (Burnley), R McGivern (Manchester City), G McCartney (Sunderland), A Hughes (Fulham).
Midfielders: S Davis (Rangers), K Gillespie (Sheffield United), M O'Connor (Crewe Alexandra), S Clingan (Norwich City), C Brunt (West Bromwich Albion), D Shiels (Hibernian).
Forwards: D Healy (Sunderland), P Thompson (Stockport County), W Feeney (Cardiff City - on loan at Dundee United), M Paterson (Burnley).
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