Gary Ballance has seen his third crack at Test cricket brought to a halt by a hairline fracture to his left index finger suffered during England’s heavy defeat by South Africa at Trent Bridge.

Ballance was struck by a delivery from Morné Morkel during England’s fourth day collapse as the tourists went level in the four-match series and, though he had told the team management he was ready to play on, a hand specialist seen on Tuesday night ruled him out of next week’s third Test.

England maintain he could still return for the fourth Test at Old Trafford the following week. But the injury opens the door for an uncapped rival to stake a claim at The Oval, with Surrey’s Mark Stoneman, Middlesex’s Dawid Malan or Essex’s Tom Westley among the contenders.

Though Ballance has struggled to make an impact on his return to the side after being endorsed by the new captain, Joe Root – he has squandered three starts in four innings with a top score of 34 – England had been leaning heavily towards an unchanged squad despite two all too familiar batting collapses in the 340-run hammering by Faf du Plessis’s side.

But now the full selection meeting that takes place at the end of the week will revolve around which of the uncapped trio comes into the squad.

Stoneman, 30, would appear the frontrunner on his new home ground, having compiled three Championship hundreds this year since his winter move from Durham, as well as two half-centuries against South Africa A in what was the opener’s first match for the England Lions.

However, the England coaching staff are keen that Keaton Jennings is given a continued run as Alastair Cook’s opening partner – his first home summer has brought double figures just once – meaning Malan and Westley will certainly be part of the debate.

Malan has averaged in the mid-40s over the past four Championship seasons and is a favourite of the Lions head coach, Andy Flower, as mainstay of the second string in the past 18 months. The 29-year-old also impressed Trevor Bayliss with his handling of Morkel when making a 48-ball 78 on his Twenty20 international debut in Cardiff in June. Westley, unlike his two rivals, is a right-hander and would thus break up England’s left-hand dominated lineup. The 28-year-old has also been a heavy domestic run-scorer in the past three seasons and can point to having already scored a first-class century against South Africa from No3 this summer with his unbeaten 106 for the Lions at New Road.

While Bayliss had endorsed the continuation of Ballance and Jennings after Trent Bridge, the England head coach will be a weakened vote on the selection panel when it comes to choosing the former’s replacement – his county knowledge remains thin some two years into the role.

James Whitaker, Angus Fraser and Mick Newell will be relied on, with Root also a key voice if not officially given a vote, with Bayliss admitting: “It’s happened before, where, if we select a guy and I haven’t seen him, you’ve always got in the back of your mind a little bit of: ‘Well, is he or isn’t he?’ You’ve just got trust the other selectors and some of the senior players we might speak to.”

England’s other injury doubt, Mark Wood, has been given the all-clear over any major damage after suffering bruising to his left heel at Trent Bridge. But one wicket in four innings this series has not been the impact expected of him so the Durham quick may well find himself carrying the drinks anyway in the third Test with Toby Roland-Jones handed a debut.

Liam Dawson remains the puzzle in England’s lineup but one that is likely to remain in place. His initial call-up, as a spin-bowling all-rounder at No8, owed much to the absence of Chris Woakes; had the Warwickshire seamer not suffered a side strain last month, then Woakes’s proficiency with the bat would have seen a more specialist spinner selected.

Whether England require six bowlers is open to debate but it is clear that Bayliss and Root consider Moeen Ali a batsman first, off-spinner second, after his four centuries last summer. Dropping him back to No8 – the role he performed in the series wins over Australia and South Africa in 2015 – and playing the extra batsman is a possibility.

But asked about this prospect, Bayliss replied: “As a batter, I’d have the shits having to bat at No8. It’s almost a waste having eight batters in the team. He had some success there but in a way, that’s papering over the cracks a little, it’s saying we’re not confident with our batting lineup. The simple fact is we’ve got to do better with the bat.”