West Ham United's erratic home form will ensure they approach the second leg on Monday with a degree of caution but Sam Allardyce and his players are within touching distance of a place in the play-off final after this convincing victory. Two first-half goals from Jack Collison, the second of which took a huge deflection off Liam Lawrence, enhanced West Ham's reputation as a team never more comfortable than when on their travels.

Having finished the Championship season with a club-record 13 away wins, including a victory here by the same scoreline in March, West Ham delivered another impressive performance on the road to leave Cardiff facing the prospect of yet more play-off misery. It is 50 years since Cardiff were in the top-flight and any hopes they had of ending that absence and joining Swansea in the Premier League were left hanging by a thread come the final whistle.

Malky Mackay's side improved after the interval but they badly lacked a cutting edge in front of goal on a night when West Ham looked much more threatening going forward and could easily have scored a third. Carlton Cole must have thought that he had killed the tie on the stroke of half-time, when he headed towards the bottom corner only to be denied by a magnificent save by David Marshall, and Kevin Nolan nodded wide when it looked easier to score in the second half.

Not that West Ham had any reason to leave here feeling disappointed. This was an accomplished performance from a team that could have been forgiven for feeling a little sorry for themselves after missing out on automatic promotion on the final day of the season. They played with confidence and conviction and never looked back from the moment Collison scored the first of his two goals in the ninth minute.

"We played very well, we got it right tactically," said Allardyce, the West Ham manager. "We created chances, scored a couple and could have had more.

"But we're only 90 minutes into a two-legged affair and anything could still happen. The onus is on us to see it through. There is no pressure on Cardiff. They can come and chase what they can. Mentally, we have to be right for that."

Upton Park has been more of a hindrance than a help to West Ham at times this season but Allardyce is confident that his players can handle the occasion. "It's draws that have cost us but we have only lost four matches at home," he said. "And we're in a position now where if we don't lose, we're through."

Cardiff can take comfort from the fact that they won at Upton Park on the opening day of the season, when Kenny Miller scored the only goal, but there was little else for them to cling to at the end of a hugely disappointing evening for the home supporters. This felt all too familiar for a club that has endured play-off heartache in the previous two years, having lost to Blackpool in the final in 2010 and suffered elimination at the hands of Reading at the semi-final stage 12 months ago.

Although Cardiff started brightly and came close to scoring twice in the opening three minutes, when Peter Whittingham's 25-yard shot skimmed the crossbar and Miller drew a decent save from Robert Green with another long-range effort, the home side soon fell behind. Matthew Taylor's lofted pass picked out the run of Ricardo Vaz Tê, and the Portuguese winger delivered a superb cross that Collison headed in at the second attempt, after Marshall had pushed the midfielder's first-time volley up in the air.

The Wales international collected his second goal in the 41st minute, when he took the ball down on his chest 25 yards from goal before firing a volley that Lawrence diverted past Marshall with his head.

Cardiff badly need a breakthrough early in the second half and Ben Turner nearly provided it with a far-post header that Cole nodded off the line. Miller, who has been going through a lean spell, later flashed a volley over and Joe Mason had a goal disallowed for offside as the game slipped away from Cardiff.

Mackay, however, refused to concede the tie was dead. "I think 2-0 is a dangerous score for the team that is 2-0 up," the Cardiff manager said. "If we go there and get that first goal it makes a big, big difference."