Arsenal enjoyed the perfect preparation for their Champions League showdown with Monaco as they maintained their hold on a top four place in the Premier League with 3-0 win over West Ham on Saturday.

Goals from Olivier Giroud, Aaron Ramsey and substitute Mathieu Flamini ensured Arsene Wenger's side will travel to the principality with their confidence high as they attempt the tricky task of overturning a 3-1 deficit from the first leg of their last 16 tie.

The third placed Gunners were on top from the start of a one-sided London derby, although it took a while for the goals to arrive.

Theo Walcott couldn't even get a shot out when he should have put the home side ahead after just five minutes.

Giroud flicked the winger through with a divine back heel that took out the whole West Ham back line but, with Walcott one-on-one with Adrian, the England international hesitated.

When he tried to get a shot off, West Ham defender James Collins was across to send him to the turf, only for referee Chris Foy to wave away Arsenal's penalty appeals.

West Ham successfully kept Arsenal at bay for a period, and might even have taken the lead when Kevin Nolan volleyed at goal from the edge of the box, but David Ospina managed to keep it out.

The first half siege really started when Ramsey attempted to score with his knee, showing fine improvisation for a high cross, but West Ham goalkeeper Adrian's response was equally impressive as he touched over.

The Spaniard then saved from another Walcott one-on-one, a Alexis Sanchez volley, and a Mesut Ozil drive.

It was a sign of Arsenal's frustration that, at one point towards the end of the first half, Sanchez seemed to try to punch the ball past Adrian.

Despite trying to use the goalkeeper for cover, though, the Chilean's attempt was seen by Foy and a booking was issued.

Yet, as anxious as Arsenal were getting, it did seem only a matter of time until an opening arrived.

It duly did, on the stroke of half-time.

Ozil, Ramsey and Giroud played a fine interchange, before the French striker checked inside and unleashed a high shot in off the post.

It capped what had been an excellent first half for Giroud.

West Ham came out stronger in the second half and might have equalised when Matt Jarvis was presented with a clear shot on goal about 15 yards out, but the winger blazed wastefully over.

The game was then disrupted when Foy had to go off injured with a calf strain, with fourth official Anthony Taylor on in his place as a gleeful chant of "You're not fit to referee" rang around the ground.

The Arsenal fans still weren't totally comfortable, though, as they still hadn't killed off the game.

Ozil's strange decision on 70 minutes didn't help his team's cause.

Through on goal and with a clear shot presenting itself, the Germany midfielder opted to chip it across the box.

The subsequent shot went just wide, but Ozil himself seemed in a far better position.

Arsenal finally improved their own position on 82 minutes as Ramsey struck to double the lead.

Giroud was again instrumental. The striker allowed a throw-in to roll past him, before exchanging a one-two with Ramsey, who hit a half-volley past Adrian.

Arsenal then made it 3-0 thanks to quick thinking between two substitutes as Santi Cazorla played the ball across the box for French midfielder Flamini to slot home.