BARCELONA (Reuters) - Barcelona forward Martin Braithwaite is set for a lengthy spell on the sidelines after the club announced on Monday he is to undergo knee surgery.

The Denmark striker has started all three of Barca's LaLiga games this season and scored twice in the 4-2 defeat of Real Sociedad in their opening game but sustained a knee injury in the 2-1 win over Getafe on Aug. 29.