West Ham United moved level on points with sixth-placed Arsenal after being held to a 1-1 draw at home to Stoke City in a dour Premier League clash at Upton Park on Monday.
Jonathan Walters put the visitors in front after 13 minutes when he finished off a training ground routine from a corner by losing his marker and firing in at the near post from 10 metres.
West Ham's fine start sees them in seventh place with 19 points from 12 games, nine behind leaders Manchester City, while Stoke are 14th with 13 points, four above the relegation zone.
Charlie Adam was among several Stoke players to block West Ham's defenders and help create space for the opener although manager Tony Pulis said the routine had failed in practice.
"We worked on it for two or three days in training but never scored a goal," he told Sky Sports.
West Ham captain Kevin Nolan said he was relieved his former Bolton Wanderers team mate O'Brien, who missed the 2009/10 and 2010/11 seasons through injury and moved to London in August, had finally notched his first goal in the English top flight.
"He's had a tough two years out with a knee injury and I'm delighted for him. I think you could see that with all the lads, there's a great camaraderie here," said Nolan.
Photograph: Toby Melville / Reuters
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