West Brom are hoping in-form striker Kanu and Diomansy Kamara can delay their departure for the African Nations Cup until the middle of January.
Kanu and Kamara are currently scheduled to temporarily part company with The Baggies on January 6 to join up with Nigeria and Senegal respectively.
But Baggies manager Bryan Robson wants the duo to remain at The Hawthorns for a further 10 days to allow them to play in the FA Cup tie with Reading and the away Premiership clash with Wigan.
Albion are now awaiting a response from the Nigerian and Senegalese Football Associations but the players have indicated they would like to remain with the West Midlands club for the extra two games.
Robson said: 'Both nations are trying to call Kanu and Kamara on January 6 but both players have asked their respective associations if they can join up on January 16.
'Kanu's first game is January 24 and Kamara's first match is 24 hours before that. That would mean they would still have a week to prepare with their teams for the opening game if they left on January 16.
'I'm asking if the two countries can leave the players with us until after the Wigan game on January 15 and then they can go after that.
'I'm not sure if the request will be granted but the players want to be involved in the Wigan game. They don't want to go before then. It's good the players are not wanting to go until then.
'The two FAs will have the final say but we've always tried to be helpful with Kanu and Kamara when they have gone away with their countries.
'We've never complained and we are just asking for Nigeria and Senegal to be helpful with us on this occasion. They would only be training. It is not as if they are going to miss any matches if they don't leave until January 16.'
Kanu has been a major force in Albion's four-game unbeaten run which has lifted them out of the bottom three of the Premiership while Kamara scored his first goal for the club in Saturday's 2-0 win over Manchester City.
Defender Steve Watson is the major injury doubt for the weekend game at Portsmouth with the hamstring injury which forced him to be substituted against Stuart Pearce's side.