Jade Dernbach's place in England's T20 side is under threat ahead of their series-opener with New Zealand on Saturday, Nick Knight told Sky Sports.
The Surrey seamer was cut from the ODI squad after a torrid time in India and, despite taking three wickets in England's second warm up T20 against a New Zealand XI on Wednesday, is not guaranteed a place in the tourists' line-up when they kick-off their campaign against the Black Caps this weekend, says Knight.
Dernbach showed what he is capable of with a valiant, if ultimately unsuccessful, attempt to limit New Zealand in the final over of the second warm up in Whangarei, which the hosts won by three wickets.
But Knight said: "As the last over was being bowled I wasn't being as dramatic to think 'this is all or nothing for Dernbach for the T20 internationals' but I thought it may have a major say."
After seeing the fast-bowler take a wicket with his first ball but then, with the scores level on his last delivery, get hit for four, Knight added: "I think he did alright but the selectors now have a major decision because he's not in the best of form. He's had a struggle in India and he hasn't really got going here.
"I think they'll stick with him but they'll think long and hard about it."
Aside from Dernbach, Knight is relatively satisfied with the current England line-up set to face New Zealand, but suggested a fifth bowler may boost their chances in the three-match T20 series.
"I don't think they'll change much at the top," said the former England opener.
"Alex Hales hasn't got going but I'm not worried about him because he's a good prospect and will score runs throughout the series.
"They'll have to consider whether they go in with five bowlers, though. They didn't do that today, they left out Chris Woakes. I think he may play on Saturday, in which case they can go with five bowlers and rely on the batters doing the job."
Meanwhile, former England quick Angus Fraser said the 2009 T20 World Cup winners still have plenty of room for improvement.
"If you look at the whole match England had six or seven top overs when Eoin Morgan and Joss Buttler got together, but the bowling was mixed," he said.
"Steven Finn, Dernbach and James Tredwell struggled - although Broad bowled well again, which is a positive.
"But there's quite a bit of work to be done to get the side into the shape they want to be."
And another ex-England fast bowler, Dominic Cork, also offered words of caution ahead of the national team's clash with a New Zealand side which defeated South Africa 2-1 in the fifty-over format 2-1 away from home last month.
"England should have learnt from New Zealand's victory in South Africa that they are a force to be reckoned with," he said.
"For me England lost it in the first six overs of the New Zealand XI innings in this warm up; New Zealand were 56-0 after six overs. England have got to take early wickets.
"But they'll look at themselves and think 'wipe this clean, now get ready for Saturday'."