Niko Kovac confirmed Lucas Hernandez has undergone a successful surgery on his knee injury and should be fit for the start of the 2019-20 season.
The France defender, who can play at left-back or centre-back, was announced as an €80 million (£68m/$90m) signing from Atletico Madrid on Wednesday after Bayern triggered his buyout clause to smash the Bundesliga's transfer record.
Lucas will not play again for the La Liga side as he went under the knife to resolve damage to the medial collateral ligament of his right knee.
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The 23-year-old will undergo rehabilitation in Germany under the watch of chief medical officer Dr Hans-Wilhelm Muller-Wohlfahrt but Kovac cannot guarantee Lucas will be ready for pre-season.