Arsenal 5-1 Benfica: Yaya Sanogo scores four in Emirates Cup
Yaya Sanogo scored four times as Arsenal beat Benfica 5-1 in the Emirates Cup.
The French striker, 21, failed to find the net in 14 appearances last season but caught the eye as Benfica were swept aside at Emirates Stadium.
In the tournament's early kick-off, Monaco drew 2-2 against Valencia.
Chile forward Sanchez, signed from Barcelona, replaced Campbell - back from a loan spell at Olympiakos and several impressive displays at the World Cup -to a rousing reception with 15 minutes left.
Colombia striker Radamel Falcao, who missed the World Cup because of a serious knee injury, made his first appearance since January as Monaco twice came from behind in their match with Valencia.
Arsenal play Monaco on Sunday before facing Manchester City in the Community Shield next weekend, while Benfica will close the tournament against Valencia.
Arsenal: Martinez, Bellerin, Chambers, Monreal (Miquel 73), Gibbs, Ramsey (Arteta 59), Flamini (Coquelin 59), Rosicky (Wilshere 59), Oxlade-Chamberlain (Cazorla 46), Campbell (Sanchez 73), Sanogo (Akpom 73).