ZAGREB (Reuters) - West Ham began their Europa League campaign with a 2-0 win at Dinamo Zagreb in Group H while Celtic threw away a two-goal lead in a 4-3 defeat by Real Betis in Group G in the opening round of games on Thursday.

Red Star Belgrade, the 1991 European Cup winners, ground out a 2-1 home win over Portuguese rivals Braga while Bulgarians Ludogorets Razgrad earned a 1-1 draw at Danish side Midtjylland in Group F.