Some key unknowns in the England side will pose fresh challenges for West Indies when their long-awaited Test series begins on Wednesday, Kemar Roach says.

Roach, who will again be crucial to West Indies' vaunted pace attack when the sides open their three-match contest at the Ageas Bowl, believes the absence of captain Joe Root from England's batting line-up leaves "some big shoes to fill" and that could work for - and against - the tourists.

ALSO READ: 'I am bowling much better now than when I was bowling 145-150kph'

"A Test match without Root, the fantastic stats he has, is going to be a bit of an advantage for us," Roach said via Zoom press conference on Sunday. "He's one that keeps the England batting together, he's done fantastically for them for the last couple of years.

"Without him it is a bit of an advantage for us, but also a little bit of a disadvantage because there's some new guys coming in that we obviously have to work out and see what their weaknesses are and try to exploit them. So it goes 50-50, but once we get stuck in and hit our straps and put the balls in the right area I think we stand a very good chance of going out there and performing well."

While Roach's first-innings 5 for 17 decimated England and set up West Indies' 381-run victory in the first Test in Barbados 18 months ago, he could potentially come up against just two of the same batsmen in England's top six this time around in Rory Burns and Ben Stokes, who will stand in as captain while Root attends the birth of his second child.

Newcomers Dom Sibley, Zak Crawley and Ollie Pope are set to show their faces in Southampton along with Joe Denly, who played the second and third Tests of England's Caribbean tour last year. Even among England's reserves are two new names after Dan Lawrence and James Bracey impressed with the bat during last week's intra-squad warm-up match.

But Roach acknowledged that England hosting presented different conditions, which would only be more unfamiliar with Covid-19 prevention measures including no crowds and the ban on using saliva to shine the ball. And he said Stokes as skipper added another layer of intrigue to the first Test.

"I'm a huge fan of Ben Stokes," Roach said. "He's a fantastic cricketer. He's very energetic, brings a lot of energy to the field and a lot of confidence when he bats or when he bowls, so I'm expecting a very free and relaxed England team to come out there and express themselves because that's the way he plays.

"It's interesting to see him captain, obviously it's the first time we're going to see it, but I'm sure that with him at the head, they're in good hands as well, so I wish him all the best."

Roach was keen to see his skipper, Jason Holder, "battle" with Stokes as captains and allrounders - the pair are No. 1 and No. 2 respectively on the ICC's Test allrounder rankings.

"It's always good to have challenges, it's always good to have battles, it brings out the best in you," Roach added. "I hope he and Ben Stokes go at it in a couple of Test matches here. They're both fantastic cricketers and I'm sure that once they're battling it will be great cricket to watch."

The touring camp have expressed concerns over their own batting line-up in recent days. A likely top five of Kraigg Brathwaite, John Campbell, Shamarh Brooks, Shai Hope and Roston Chase managed just 29 runs between them in West Indies' second intra-squad warm-up match, a rain-affected four-day game at Emirates Old Trafford last week.

While Brathwaite, Hope and Brooks did manage fifties in the first tour game, they were unable to build on that in the second as West Indies' first-choice pace attack of Roach, Shannon Gabriel, Holder and Alzarri Joseph reduced their side to 49 for 5 in their only innings.

Holder managed just seven runs, facing fewer than 30 deliveries in three warm-up innings, and he bowled only five overs across the intra-squad matches while nursing an ankle problem.

ALSO READ: WI batsmen 'need to stand up and make a difference' - Brooks

But Roach had every confidence that the bating unit - and Holder - would be set to go come Wednesday morning.

"They're trying their best to get going in the series," Roach said of the West Indies batsmen. "I think they've made some strides. They've had some discussions, I've been told, and I'm confident in the guys. Their work ethic has been spot on and they've done everything to put themseves in a good head space and perform in this series.

"I'm confident in them. I'm sure they can go out there and get the job done so I'll just sit back and watch them bat. Hopefully someone can get a couple hundreds in this series and we can take it to the English.

"Jason is very important to us going out there. He had a niggle early in the camp, he's been treating that and I think he's ready and rearing to go now. I'm sure that he can come out here and get himself ready and mentally prepare to start on Wednesday so I'm not really too concerned about it."