The brash substitute thought he would do something about Cesc Fabregas conducting the Gunners' orchestra with such ease. A sharp elbow into the Spaniard's throat soon ruffled the visiting captain's feathers.
It was Diamanti's free-kick that led to Carlton Cole breathing life into what had been a horribly one-sided affair and, when referee Chris Foy finally decided to award Gianfranco Zola's men a penalty at the second time of asking, guess who stepped up to level the scores?
Arsene Wenger will be tearing his hair out at the way his side failed to kill off a Hammers team that looked every inch a bottom-three side in the opening stages.
Robin van Persie had already tested Robert Green when the England keeper made a terrible gaffe from Bacary Sagna's cross to gift the Dutch striker the simplest of openers on 16 minutes.
It is not wise to aid Arsenal along their way and, although Mark Noble and Cole went close, it looked all over when Fabregas's shot deflected out for a corner and van Persie swung it over for William Gallas to climb well to head in from close range.
37 minutes gone and seemingly game over.
In the second half, there was what amounted to token Hammers pressure but without any genuine belief they could claw their way back into a game Arsenal were controlling. Fabregas was inches away from sealing victory with a long-range piledriver that had Green clutching at thin air and the visitors were almost toying with their London rivals.

Cue Diamanti's arrival as substitute. The 26-year-old had two cracks at goal that went wide, flattened Fabregas and generally hustled the visiting defence out of their stride.
When his 74th-minute free-kick forced a flying save out of Vito Mannone, his compatriot inexplicably palmed the ball to his left, sending it to the centre of the goal, where Cole gleefully pounced with a predatory diving header that displayed his qualities in front of goal.
Two minutes later, Scott Parker's surge into the box was halted by Gallas's silly flick of the leg. It should have been a penalty but Foy waved play on. Parker could not believe it but, three minutes later, the official did point to the spot.
Cole went down under Alex Song's firm challenge but it seemed a harsh decision. Mannone was booked and there was a considerable amount of gamesmanship from the Gunners as Diamanti prepared to take the kick. Unperturbed, up he stepped at last to slam a left-footed shot into the corner of the net.
Parker made a great recovery challenge on Fabregas but appeared to handle the ball on the ground and was shown a second yellow card five minutes from time to leave his team-mates up against it.
The final moment of drama came when van Persie dived to head what looked the certain winner but Green, so at fault with the opener, redeemed himself by blocking superbly with an outstretched leg.
Breathless stuff which could never have been forecast before a certain Italian's introduction. It will definitely make his compatriot on the touchline flash a few more of those trademark grins this evening.
This article has 12 comments
Bring off Eboue and bring in patirck viera. shore up the defence but otherwise Arsenal were just unlucky not to win.
By din. Posted October 30 2009 at 3:18 PM.
I have to repeat my comments I have made for 2 Years.
No Team in the world can expect to win silver with 10 men on the pitch week in week out.
The players left in this scenario are "last touch" Eboue "52 chances" Bendtner. Both played against West Ham on Sunday. Add "erratic" Diaby and you have 9 men on the pitch.
Which showed having been 2-0 up.
Eboue was replaced by Bendtner in the 70 min. which meant Arsenal were still left with 9 men on the pitch.
Eduardo and and Nasi were left on the bench.
They both should have come on, Eboue and Diaby off.
That didn't happen and Arsenal lost 2 points !
Own up Arsene and get it right for the rest of the season, otherwise the silverware won't be there for a 5th season !!!!!!!!!
By John Barry. Posted October 27 2009 at 12:02 PM.
Ok..... so everybody is tip toeing around Eboue since the whole booing thing. Is that reason to leave him on the field in a wide position when he doesnt know how to cross a ball?
Diaby was non existant, as was Arshavin. nobody wanted to fight for the ball. Song who so far this season has been excellent, tried to run the ball too much and didnt really battle to get it back.
I follow this club with my heart but it hurts to see them let teams back into games like this. It really does seem like the players believe they are to good to give 100% against the lesser teams like AZ and West Ham.
Lets see how the KIDS do against Liverpool in the cup. the epitomize our clubs spirit and i wish some of the established players would take notice
By Paddy Doherty. Posted October 26 2009 at 8:27 AM.
I love Arsenal. Our main problem is Diaby, sometimes I feel he is not our style although he always try to gather oppenents aiming to create space for team mates but he can not do it the right way I prefer if stick to our passingmove style. for sure nasri return will see him off.
By NAZ. Posted October 26 2009 at 7:49 AM.
I am sick & tired of watching Diaby play because if you follow him, he is one who loses the ball a lot and never fighting back for it from the opponent, always waiting for balls from his team mate and dribbling it till he loss it. Not a team player as I have observe him for a long time. Even though I may be a die hard Arsenal supporter but sometime I feel they deserve losing matches especially when they play Diaby. Was hoping that he be sold off before the season begin but.... Wenger please do something with him.
By Dan Leo. Posted October 26 2009 at 3:04 AM.
The league s still young but you do wonder how long are we gonna wait for this title, why give away points so cheap, am gutted but still love this club, i love Arsenal, i love this club
By Bafano. Posted October 25 2009 at 10:07 PM.
WHAT DOES IT TAKE TO GET THROUGH THE ARSENE AND HIS TEAM . THE SCRIPT WILL NEVER CHANGE " IF YOU DONT SECURE THE THREE POINTS YOU WIN NOTHING !!!!!!!!"
By KRIS. Posted October 25 2009 at 8:33 PM.
2-0 UP EARLY ON WITHOUT EVEN GETTING OUT OF THIRD GEAR TWO THINGS SPRUNG TO MIND,WEST HAM ARE AWFUL AND WE WILL WIN 6-0,BUT AS USUAL ARSENAL THOUGHT THEY COULD STROLL AROUND WITHOUT BREAKING A SWEAT,WRONG AGAIN! ARSENE WENGER KEEPS USING THE WORD "NAIVE" TODAY HE WAS NAIVE IN NOT SEEING TOP CLASS PLAYERS PLAYING FOR WAGES AND NOT THE BELOVED CANNON ON THEIR SHIRTS,OK NOT BEING TECHNALLY GOOD ENOUGH IS FINE,BUT WHEN YOU SEE YOUR BEST PLAYERS LOSE THE BALL AND NOT BE BOTHERED TO FIGHT AGAIN,THAT IS CRIMINAL.TO BE CHAMPIONS YOU NOT ONLY NEED SKILL,YOU NEED GRIT AND 95 MINUTES OFSOLID DETERMINATION,I TRULY BELIEVE THIS ARSENAL TEAM DOES NOT POSCESS THESE LATER ATTRIBUTES WHICH COULD BE DEVASTATING FOR ALL GOONERS THIS SEASON.
By JIM MILLAR. Posted October 25 2009 at 8:17 PM.
Once again within 3days Arsenal gave away
another victory. Last Wedneday they did the same.
Wenger must shoulder the blame for again fielding Eboue who lost the ball several times
he even tried to score from an impossible place. Another player was Diaby. Wenger
failed to take them off till the final 15 mins, when it was too late.
Why is he not using Ramsey ??
Why he failed to play someone else instead of Diaby.?? If Wenger continues with this attitude than he can say goodbye to any cup.
By A.Messina. Posted October 25 2009 at 7:51 PM.
what, we should have a penalty before the cole one , and we gifted them their goals
By east london hammer. Posted October 25 2009 at 7:09 PM.
one sided affair --no it wasnt --what game was you watching
By west ham fan . Posted October 25 2009 at 7:07 PM.
arsenal will NEVER win anything.they score one goal,they start showboating thinking they have won the Premiership.they are NOT winners.
By colonel M. Posted October 25 2009 at 6:56 PM.