Atlanta United fullback Sal Zizzo likely will miss the remainder of the MLS season because of a knee injury that will sideline him for the next 3-4 months.

He recently underwent surgery to repair the meniscus in his right knee. He suffered the injury during training.

Zizzo, 31, signed with Atlanta United as a free agent. He made six appearances with one start this season.

The team has yet to release an update about fullback Mikey Ambrose, who suffered an injury playing for Atlanta United 2.

Atlanta United has options at fullback, but the position is thin.

Franco Escobar will miss Saturday’s game against Toronto at Mercedes-Benz Stadium because of yellow-card accumulation. Manager Gerardo Martino could use Julian Gressel, Andrew Wheeler-Omiunu or Miles Robinson in the position of right fullback, should he go with a four-man back line.

Ambrose, 24, will be the second left fullback to miss a significant portion of the season after Greg Garza underwent surgery to repair his injured shoulder. He made 10 starts. Ambrose logged eight starts in nine appearances. Chris McCann has slotted into the position. He has 12 starts in 13 appearances this season.

The transfer window is open until Aug. 8, so Atlanta United could try to acquire a player to strengthen the fullback slot. MLS rules allow each time to use one season-ending injury slot on a roster to create the ability to sign or promote another player.