Eddie Patterson insists Richard Clarke will remain at the Oval unless Glentoran can source a replacement midfielder in January.
Clarke has been linked with Premiership clubs Crusaders and Ballinamallard United during the transfer window.
Glentoran are currently in talks with Ruaidhri Higgins, who was released by League of Ireland outfit Derry City at the end of December.
Patterson admits Clarke’s future will depend on what business can be done between now and January 31.
“We are still in talks with Ruaidhri Higgins – hopefully something can be done in the next week,” the Glens boss said.
“Those talks are ongoing.
“I have told Richard that if I can get someone in during January, then we can look at his situation.
“We are targeting that position in the transfer window so we will see what materialises over the next couple of weeks.
“We were interested in Brian McCaul of Linfield, but he has been ushered towards Glenavon.
“So we are talking with Higgins, and one or two others, and hopefully we can get something completed.”
Glentoran have already signed former Linfield and Inverness striker Curtis Allen who looks set to make his debut in Saturday’s massive Irish Cup fifth round tie against Portadown.
Allen signed a three-and-a-half-year deal with the Oval club last week but missed the 2-2 league draw with the Ports.
Patterson admits Saturday’s cup showdown at Shamrock Park will be a “massive test” for the holders – in what is a repeat of last season’s semi-final.
“Portadown have held the Indian sign over us this season. They have beaten us twice and we had the 2-2 draw last week,” Patterson said.
“But this is a new game, and we are the holders of the cup and want to progress. So we will be going to Shamrock Park determined to book our place in the next round.
“Obviously we could have had an easier draw. You always want a home draw, and preferably against lower-ranked opposition. Well, we have been drawn away to one of the best teams in the country.
“It doesn’t get any harder that this, but you have to win big games to lift trophies, and this is a big game.”
Patterson has voiced his “disappointment” at Ronnie McFall after the Ports boss criticised Mark Clarke following last week’s stalemate at the Oval.
McFall claimed Clarke should have been sent off for a tackle on Neil McCafferty.
“I was disappointed with Ronnie’s comments after the match,” Patterson said.
“Two of our players picked up injuries because of bad tackles from Portadown players, but we didn’t feel it necessary to start singling anyone out in the press.
“It’s not the first time Mark Clarke has been unfairly picked on. He is a big, strong midfielder, and there are plenty more like him in the league.
“Ronnie’s comments have only served to stoke things up ahead of Saturday’s game, and it does put pressure on the match officials.”