Latvia international Vitalijs Maksimenko has joined from Brighton along with Charlton striker Jordan Cook until April 17.
The versatile Maksimenko, who can play anywhere down the left flank, moved to the Amex from Skonto Riga in the January transfer window after impressing during a spell training with the Seagulls last year.
""He's a strong lad. He's quick, he's left-footed and he's got himself in the Latvia national team," boss Gary Johnson told the Western Gazette.
Cook, who has made nine Addicks appearances this season, began his career with Sunderland and spent loan spells with Darlington, Walsall and Carlisle before signing for the Black Cats back in July.
"Our scouting system identified him (Cook) as a player," Johnson explained. "We were going to take him on loan with a view (to sign permanently) but obviously Charlton took him.
"It's nice for us to have him now, it's certainly cheaper, it's doing the lad a favour, Charlton a favour and hopefully us a favour."
The pair are available for the match with the Robins on Tuesday.