Luxemburg's FC Dudelange produced a stunning upset in the Champions League qualifiers with a 1-0 home win over Austrian double winners Salzburg on Tuesday.
Cristiano Ronaldo scored on his return to the starting line-up as Manchester United sealed a place in the Europa League knock-out rounds with a 3-0 victory over Sheriff Tiraspol at Old Trafford on Thursday.
IMAGES from the Europa League matches played on Thursday.
Artificial turf will make its debut in the finals of a FIFA competition this month and, though officials say the World Cup is sacrosanct.
Manchester United kicked off their Europa League campaign poorly, losing 0-1 at home to Real Sociedad, while Arsenal's new signing Marquinhos scored in a 2-1 win at FC Zurich on Thursday.
Rashford scores a brace as Man United fight back to beat Omonia
In the day's other fixtures, Croatian champions Dinamo Zagreb took a big step towards the next stage with a 2-0 win at Georgians Saburtalo and Copenhagen won at Welsh side The New Saints by the same score.
Red Star Belgrade, who won Europe's premier club competition in 1991, engineered a 2-0 home victory against HJK Helsinki thanks to a Richmond Boakye header and substitute Milan Pavkov's sweeping 90th-minute finish.
Jordon Ibe scored a superb equaliser as Liverpool's pre-season tour ended in frustration after they were held to a dull 1-1 draw by a Malaysia XI on Friday.
Former European champions Red Star Belgrade, Ajax Amsterdam and Celtic all made it comfortably through to the third qualifying round of the Champions League on Wednesday after surviving away legs.
Ajax Amsterdam, returning to the stadium where they last won the Champions League 20 years ago, squandered a two-goal lead to draw 2-2 against 10-man Rapid Vienna on Wednesday.
Holders Sevilla maintained their Europa League challenge with a 1-0 win over Rijeka in a winner-takes-all clash on Thursday.