Cricket correspondent Tony Adamson reports from Jerez (Radio 5 Live)

Ulsterman Clarke, who is third in the Order of Merit going into final event of the season, fired a five-under-par 67 for a share of the first-round lead.

He is three shots clear of the two other players who can claim the European crown - favourite Colin Montgomerie of Scotland and second-ranked Lee Westwood, who both carded two-under 70s.

To finish top of the rankings Clarke has to win the event and then hope his two rivals fail to make the chasing pack.

In the swing: Clarke drives on the par-five third

Clarke's 67 took him to the top of the leaderboard, alongside five other players - Scotland's Gordon Brand Jr, Australian pair Greg Chalmers and Peter O'Malley, Jarmo Sandelin of Sweden and Germany's Alex Cejka.

Clarke made his intentions clear early on, moving to three-under-par at the halfway stage, thanks to a 40-foot eagle putt that gave him an eagle on the ninth.

Westwood falters as Monty hits back

Westwood got off to a flying start and completed the best outward half on the first day of the event.

The Englishman, who is suffering from a side strain, birdied the first three holes and went to the turn in four-under-par 32.

Montgomerie agonises as a birdie putt just misses at the sixth

But his game then fell away and he dropped two shots on the way back to the clubhouse.

Montgomerie could only manage a level par 36 for the opening nine.

But an eagle on the 12th followed by a birdie at the last kept him in touch with the leaders and alongside Westwood, who remains the major threat to him securing an unprecedented sixth successive Order of Merit title.