Rory Lamont returns to the Glasgow team on Sunday for their RaboDirect PRO12 clash against Zebre almost 12 months after breaking his leg on Scotland duty.
The back-three player has undergone two operations since suffering the injury in Scotland's RBS 6 Nations clash with France last February, and made his competitive comeback for Dundee High last month.
Meanwhile, Tongan prop Ofa Fainga'anuku has extended his contract until the end of the season, subject to being granted a work permit.
Warriors head coach Gregor Townsend said: "We were very keen to keep Ofa involved with the squad as he has made an excellent impact since he joined us.
"He brings yet another dimension to our game and is an outstanding person who has fitted in so well at the club and worked hard to improve. It's great news that he's agreed to extend his contract.
"The return of John Barclay and Rory Lamont from injury is also a real boost for us."
Scotland A captain Ryan Wilson is among eight players in the Glasgow side who beat England Saxons away from home last week.
Townsend said: "Obviously a lot of our players are involved with the Scotland set-up but the strength of the side we are able to field is a testament to the quality of players we have at the club.
"Any game away in Italy is a real challenge and we have to make sure that we are sharp and ready for Zebre.
"I thought all of those who were involved in the Scotland A game were terrific and showed real fight, but we'll need the same level of intensity this weekend as well if we're to leave Italy with the win."