Paul Caddis will remain with Rovers this week as the squad flies out to Austria for a warm-weather training camp.
The 29-year-old defender has been on trial with the club since the start of pre-season and played the first half of Rovers' 2-1 victory over Barrow on Saturday.
Caddis has previously played under Rovers boss Tony Mowbray at Celtic and the manager insists he is leaving the door open for the Scotland international to earn himself a permanent deal.
"I like Caddi," said Mowbray. "I had Caddi as a kid when he was at Celtic.
"He's a very, very good footballer. He's played 200-odd games in the Championship.
"He's different from Ryan Nyambe. He's a different type of full-back. Nyambe is power and pace and athleticism. Caddis is a more cultured footballer who keeps the ball and passes it around, and I think we might need both types as the season unfolds.
"We're going to take him abroad and we'll make a decision."