Graham Onions' chances of playing in the first Test against South Africa were receded further when he was unable to train on Wednesday at The Oval because of a hamstring strain.

Onions, the Durham fast bowler, is in England's 13-man squad as an extra pace bowler and after playing in the third Test against West Indies at Edgbaston had hoped to beat Tim Bresnan and Steven Finn for a place against South Africa. But he was not involved in Wednesday morning's net practice.

He has not yet been ruled out of contention to play when the first of a three-Test series starts on Thursday but the injury has not done his prospects any good. Even if fully fit, Onions faced stiff competition to fill a third seamer role, with Bresnan and Finn the leading candidates for the position.

Onions has taken 32 wickets at 29.90 in nine Tests for England - including 10 wickets as England regained the Ashes in 2009. But he suffered a career-threatening back injury and was ruled out of the 2010 season, only returning to Test action as James Anderson and Stuart Broad were rested for the Edgbaston Test this summer, where he returned 4 for 88.