Blackburn Rovers midfielder Corry Evans is an injury worry for Northern Ireland's forthcoming Euro 2020 qualifiers against Estonia and Belarus.
Evans, 28, came off after 68 minutes of Rovers' 4-2 defeat to Sheffield Wednesday on Saturday and has undergone a scan on a hamstring problem.
NI manager Michael O'Neill expects him to join up with the squad on Monday.
"There is a little bit of a doubt about Corry. We'll see how he is as the week progresses," said O'Neill.
"Will Grigg and Gareth McAuley are two that we will monitor over the week but everyone else is fine," he added.
Evans has been capped 52 times and scored two international goals, including one in Northern Ireland's last game - a 2-1 Nations League defeat by Austria in November.
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Northern Ireland face Estonia at Windsor Park on Thursday and host Belarus at the same venue on Sunday, with the Netherlands and Germany the other teams in their group.
O'Neill must already plan without midfielder Oliver Norwood, who opted out of the squad for the opening Group C qualifying games for "personal reasons".
The NI boss has expressed concerns over the lack of first-team action enjoyed by many of his squad in recent months but skipper Steven Davis played a full 90 minutes for Rangers at the weekend.
Grigg was on target in Sunderland's 2-1 League One win over Walsall, Liam Boyce found the net after being recalled to the Burton Albion starting line-up and Niall McGinn was on target in Aberdeen's 1-1 draw with Livingston.
"There's a great spirit in the group but we know the challenge that lies ahead in terms of the quality of the teams we have to play," said O'Neill.
"We need to build momentum so we will go and attack and try to win the games. We have plenty of attacking options.
"We need to play with the same intensity as we have in recent years and look for the same level of performance.
"We have a lot of pace in the team and the young lads have brought a freshness to it but we're still reliant on those players who have been consistent for us over the years as well."