Recovering Nathan Patterson will be given two more training sessions to prove his fitness ahead of Scotland's World Cup qualifying blockbuster with Ukraine.
The 20-year-old right-back has been out for two months after ankle surgery but Steven Naismith has revealed the Everton star is in contention for the big one on Wednesday night.
Boss Steve Clarke previously gave a cautious verdict on Patterson's fitness but he appears to be now trending in the right direction.
Now the Scotland coach believes the man who secured Rangers' record transfer fee in January will stand up and be counted if he wins his fitness battle.
After a training session at Scotland's base in Oriam, Edinburgh, Naismith said: "Nathan was on the pitch.
"He is obviously the one who came in with being injured but he has the next two days on the pitch to show that he is ready and fit.
"I think he is probably one of the ones in the squad that I have compared, in terms of his natural fitness, to Alan Hutton, who went long periods and never played (for his club) but performed well for Scotland.
"Nathan has shown that when he wasn't playing for Rangers, he played for Scotland, he played very well.
"So from that side everyone is comfortable that he could be ready and be in contention. But there is still two days for the manager to pick the team."
Naismith does not believe skipper Andy Robertson, whose Liverpool side lost the Champions League final against Real Madrid in Paris on Saturday night, will need picking up when he joins up with Clarke's squad on Sunday night or Monday.
He said: "When he meets up, naturally the players and everybody will have that chat about the experience, the build-up, the way the game went.
"From now until the game there is a lot of information to the players and that becomes the focus.
"The disappointment is going to be there but his experience now of these occasions is far greater than anyone else in the squad.
"Once he comes into the squad and the environment changes, the focus then changes and the reward of this game is just as big, he could be leading his country to a World Cup in one game's time if we can get the win.
"Robbo is a class act, a leader and he will be ready for Wednesday, no matter what, I'm sure.
"He has shown that he loves playing for his country, it is one of the biggest honours you have so to take them to the Euros and have the prospect of taking them to a World Cup will be the thing that drives him, I'm sure."
It was confirmed earlier that Ryan Jack is out of the squad to face Ukraine, with Clarke drafting in the uncapped Allan Campbell as a replacement.
The 30-year-old Rangers midfielder, who finished the season with a goal in the Light Blues' 2-0 Scottish Cup final win over Hearts, has reportedly picked up a calf injury.
Jack will also miss the final against Wales in Cardiff should Scotland get through their semi.
Clarke has brought in Luton midfielder Campbell after the 23-year-old former Motherwell man's impressive season in the Sky Bet Championship.
