YAYA Sanogo, French striker with sprawling, bambi like legs, stole the thunder yesterday from Arsenal's £32million record signing Alexis Sanchez.

The 21 year striker, his career hit by injuries and too much expectation, became the first Arsenal player to score four goals in any game since Andre Arsahvin against Liverpool in 2009.

His goals crushed the Portuguese champions who twice last year beat North London rivals Spurs.

Benfica don't do friendlies and this was a humiliation.

Sanogo left the field to be replaced by Sanchez and you could not split the cheers.

Go-go with Sanogo.

This is the seventh year of Arsenal's Emirate's Cup and has been a guide line to their season.

Previously they have fluffed it.

Yesterday they laid down a season marker that will be hard to beat.

They started with a side that is expected to fill the subs bench and finished with one that will be hard to argue against.

Manager Arsene Wenger made a statement in forking out £52millon on new players this summer.

His alleged second string made a bigger one.

Sanogo has that same languid style of former Arsenal player Adebayor. Yet he is just as effective.

He looks clumsy. Makes mistakes but is there when it matters.

Other bonuses was the form of Joel Campbell, right back Hector Bellerin and keeper Damian Martinez. Campbell was infectively on trial, with a host of clubs watching to make a £13million bid, with AC Milan's top scout seen making notes.

He was, he played wide right, a position Theo Walcott has made his own when fit.For Costa Rica during the World Cup he operated just behind their main striker and at Arsenal he is well down the pecking order on that list.

He started well with one or two mesmerising moments but real hero of the opening skirmishes was ex-Barcelona Spaniard Bellerin, a tricky customer when in full flight.

Made you wonder why Wenger went heavily in cash to sign Mathieu Debuchy from Newcastle for £11million.

Bellerin is a player worth watching.

Campbell fluffed a chance to put his name in neon when Aaron Ramsey cleverly lobbed him clear but the 22nd effort was scuffled wide.

Sanogo looked way off the pace at the start, his first touch led to another trying to win the ball back.

You could, however, never fault his commitment and his goal was a testament to his big heart and skill when odds are against him. He wasted a simple chance in the 24th minute, lunging in to turn a Bellerin cross wide but then put Arsenal ahead two minutes later.

Ramsey, seizing onto a Bellerin pass, got almost to the by-line and crossed for Sango to cleverly scored with the inside of his right foot.

Calum Chambers made his home debut following his shock £16million move from Southampton and for a 19-year-old he didn't look uncomfortable although there is much learning to be had.

Arsenal welcomed back Alex Oxlade-Chamberlain following his injury and looked fresh and ready to reclaim his place in the side and be an asset to Arsenal and England once more.

Bellerin made Arsenal's second goal in the 40th minute with a sweet, nicely weighted cross from the right that Campbell turned into the gaol with his left foot easier than it seemed.

Sadly, a minute later he fluffed a golden chance by hitting wide as Arsenal again waltzed through Benfica's defence.

No matter. Arsenal were back again a minute later to add their third. Ramsey chipped out wide left to Capmbell who crossed for Sanago to score.

His story wasn't over. A minute later he scored again, turning in a right wing cross from Kieran Gibbs.

Within two minutes he added his fourth. Campbell put Ramswey clear to shoot, only for Benfica keeper Moraes Artur palm out for the shot onto the welcoming feet of Sanago.

Benfica pulled one back through Nico Gaitan in the 61th minute but by then it was circus time and the warm applause for the arrival of Sanchez.