It was the second spell that impressed. The first - four overs for 21 runs - was respectable enough. But Jofra Archer needs more than respectable: he is not, currently, in England's 15-man World Cup squad. And he has only five more ODIs after this to persuade the selectors he should be.

But that second spell offered hints of weapons that England do not currently have. It offered a sharp (86mph), well-directed bouncer that had George Dockrell jerking his head out of harm's way. It offered a sharp (90.3mph), well-directed yorker to end the dangerous innings of Mark Adair. And it offered a well-disguised slower ball - every bit of 23mph slower than the deliveries that proceeded it - that rendered the quicker balls (he twice produced deliveries of 91.1mph in that second spell) all the more dangerous. With memories of England's recent travails in the Caribbean fresh in the mind - all those times they had no answer to Chris Gayle's power - it was, in many ways, a persuasive performance.

The harsh truth of selection, however, is that it is not enough just to impress: Archer has to impress more than his rivals for the role. And while he claimed one wicket - albeit an eye-catching one - and showed some of the pace and incision that renders him such a seductive contender, his rivals ground out worthy performances that reiterated the view there is not an obvious vacancy in the squad.

In a BBC interview just before the toss, Archer admitted that nerves had limited his sleep and accepted that he felt as if he were on "trial". That is hardly surprising: not since Kevin Pietersen or, maybe, even Graeme Hick has an England debut been more anticipated. The changes to the qualification period required to represent England - from seven to three years - were made, many think, just to accommodate Archer (it hardly matters whether they were or not; it's perception that counts in such circumstances) while some of the recent comments of his new team-mates did not suggest his arrival was universally popular.

Take the words of David Willey, his opening partner here, who suggested in the Caribbean that he had doubts over the wisdom of unsettling England's unit on the eve of a tournament for which they have been building for four years. "Whether someone should just walk in at the drop of a hat because they're available, whether that's the right thing, I don't know," Willey said. None of that, or the furore that greeted Chris Woakes' slightly clumsy but more than slightly twisted "immoral" phrase, can have helped Archer. If there has been any upside to the Alex Hales debacle of recent days, it is that Archer has had a little respite from the spotlight.

But it would hardly be surprising if that opening spell bore the sign of nerves. And any hopes he had of settling into it were dashed when Paul Stirling laced his first delivery - an entirely respectable ball that was nowhere near a half-volley - through the covers for four. Three more boundaries followed in that spell, though all were more due to Stirling's ability than any failure on Archer's behalf. He beat the bat a couple of times, but there were no yorkers, no bouncers, no slower balls and noticeably less movement than Willey managed. His most impressive moment in the opening hour of the game was a diving catch at mid-on to achieve the breakthrough. If he had any doubts about the standard of international cricket, they had been banished.

This was not, perhaps, the easiest environment in which to make his debut. After all the glamour and noise of the IPL, Archer changed for this game in a prefabricated unit (there are few permanent features at this ground), bowled in front of what might generously be described as half-full stands and in conditions in which a polar bear would not go out without a muffler. He is not the first cricketer who has been asked to adapt to a 20-degree temperature change in a week - Joe Denly had a similar acclimatisation to make after his own stint in the IPL - but it is worth bearing in mind that he was undergoing this 'trial' in somewhat unfamiliar conditions. The surface - slow and low, as it was - probably negated his talents while playing to a couple of his colleagues' stronger points. On the quicker, harder surfaces anticipated in the World Cup, that will not be the case.

So, can we presume Archer is now certain to be in that World Cup squad? Well, no. It's not that simple. Tom Curran and Liam Plunkett, his most likely contenders for that middle-overs bowling spot, claimed seven wickets between them here and each conceded fewer boundaries than Archer. Their skills may be less eye-catching, but they have credit in the bank and more experience in the format. They're not going down without a fight. The selectors have a tough decision to make.

They don't, thankfully, have to make it just yet. But with Woakes, Mark Wood, Ben Stokes and Moeen Ali all certain to return to the side in the coming days, the opportunities to impress for some of these players could be limited. Archer, in particular, may have to be judged on a tiny sample size.

You might be wondering why it is only Plunkett and Curran who are looking over their shoulders at Archer at this stage. Well, Wood and Woakes appear certain, if fit, to win selection. Willey also seems likely to gain inclusion on the basis of the variety - his left-arm angle - he offers and the fact that he gains some movement with the new ball. With many World Cup games starting at 10.30am - when the conditions may aid his style of bowling - and with Wood and Woakes requiring management to survive the schedule, Willey provides an obvious new-ball alternative. He is a much-improved death bowler, too.

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Denly's place in the World Cup squad also appears safe. Which is remarkable, really, given that this was his first ODI for a decade. And while his maiden ODI wicket - achieved with a stumping off a filthy leg-side wide - was more testament to smart keeping than good bowling, the team management have decided he is the utility player, who can bat and field in any position and fill in for one of the spinners if they suffer a short-term injury, and plug any holes that may appear over the course of the tournament.

Which leaves Archer vying for that last seam-bowling spot with Curran and Plunkett. And while the figures of both were decent, there were moments - such as when Adair heaved Curran for two sixes in an over or when the variation between Plunkett's slower ball and stock delivery seemed negligible - when you couldn't help but wonder if England weren't already really quite well-served by fast-medium seamers and that Archer's skill might prove a valuable point of difference.

It was an impressive second spell. But whether such fleeting evidence is enough to win selection remains to be seen.

"If today goes well, there will be a tomorrow," Archer had said enigmatically before the toss. The selectors really do face a tough decision.

George Dobell is a senior correspondent at ESPNcricinfo