Christian Pulisic has been ruled out of AC Milan's squad for Saturday’s Serie A clash with Lazio after manager Massimiliano Allegri confirmed his absence. The American, who scored the decisive goal in last weekend’s derby win over Inter, withdrew from training Wednesday with muscular discomfort - another setback. Milan went on to win 1-0 without the U.S. international.During his pre-match news conference, Allegri alluded that Pulisic would not be available for the weekend fixture at San Siro."Pulisic is unlikely to play, although there are still two days until the match and anything can happen," Allegri said. The Rossoneri have moved quickly to adjust their tactical approach, with Christopher Nkunku partnering with Rafael Leão in attack. The Frenchman has only started two Serie A games so far this season and will look to make an impact in a rare starting opportunity. Leão scored the game-winner in 51st minute. According to La Gazzetta dello Sport, Pulisic's latest issue is described as a “thigh strain” after recently returning from a previous injury layoff. The report notes that he has been working to accelerate his recovery, including increasing the intensity of individual training sessions, while Milan’s medical staff has recommended a more cautious approach.The coaching and medical staff are not expected to take risks with the injury, as it affects the same leg that sidelined Pulisic earlier in the season.Pulisic’s setback comes during a strong start to his season, with seven goals in 10 appearances across all competitions. He previously missed four games with a hamstring injury sustained during international duty with the United States in October. The American returned to action as a substitute in Milan’s 2-2 draw with Parma on Nov. 8, then started and scored the winner in the derby against Inter on Nov. 23.While the exact duration of Pulisic's absence remains unclear, Milan face a demanding schedule in the coming weeks that could influence his return to action. The Rossoneri will travel to face Lazio again in the Coppa Italia on Dec. 4, followed by a Serie A clash against Torino on Dec. 9.