"Tests have confirmed that Sergio Busquets has a hairline fracture on the fifth toe of his right foot. He will be out for approximately three weeks," said a club statement on Thursday.
Busquets was taken off for Andre Gomes in the 61st minute of Barca's last-16 second leg against Chelsea, which the Catalans won 3-0 to go through to the quarter-finals of Europe's elite club competition for an 11th consecutive year.
He will miss Barca's Liga games at home to Athletic Bilbao on Sunday and away to Sevilla on March 31, as well as Spain's international friendlies against Germany and Argentina.
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Busquets, 29, has played in all of Barca's Champions League games this season and only missed three of their league games.
Barca will learn their Champions League quarter-final opponents when the draw takes place on Friday. The first leg games are on April 3 and 4, with the return games on April 10 and 11.
(Reporting by Richard Martin; Editing by Toby Davis)
