Jos Buttler in line for Test keeper's gloves after Jonny Bairstow injury

England captain Joe Root has admitted it's "likely" that Jos Buttler will keep in the first Test against Sri Lanka.

While Jonny Bairstow is said to have made "good progress" in his recovery from an ankle injury, he was not able to train with the rest of the squad on Monday and is most unlikely to play any part in the first two-day warm-up match that starts in Colombo on Tuesday.

Ben Foakes, who was called up as cover for Bairstow, has now joined the squad but Root suggested that Buttler, who kept for part of the Trent Bridge Test and the entire Southampton Test during India's tour in the summer, is the more likely option.

"It's probably the likely scenario [that Buttler plays]," Root told the BBC. "But the reason we called Ben up is he's a high-quality wicketkeeper and gives us another way to balance the side up. It's a nice position to be in.

"Jonny would be a big loss but we've got some great players that can come in and rebalance the team. He's actually made good strides in the last week or so and he's recovered a little bit quicker than we anticipated.

"But we've got to make sure he's fit and ready to go for as long as possible and not just play one Test and then miss a huge chunk of an important winter."

Root also suggested that he himself would continue to bat at No. 4 in the Test side. He dropped back to the position ahead of the final Test against India and, while there had been talk of England batting Moeen Ali at No. 3, it currently seems more likely they will field Keaton Jennings, Rory Burns and Joe Denly in those top three positions.

"I think I will be batting at No. 4," Root told Talksport. "Certain situations may dictate the order and we don't need to be as set in stone as having a really rigid order but for most of it I'll look to bat at four."

The game on Tuesday and Wednesday is not first-class and may feature more than 11 players a side. The arrangements are not confirmed but it seems likely England will try to bat for the whole of one day and bowl for the whole of the other.

Root said he has a "strong idea" of what the Test side will be and may look to give as much time in the middle as possible to some of those batsmen who bat much during the limited-overs series. And with all three spinners - Moeen, Jack Leach and Adil Rashid - likely to play in Galle, there may be little room for seamers.

"I've got a strong idea of what the core of the side looks like," Root said. "But one of the things we can take into account is the surface and the conditions. It might not necessarily be the team that played in the summer, but that's an exciting thing. We're going to try and make sure we have a very balanced side that gives us the best chance of winning in these conditions.

"We saw in the one-day series people like Jos and Moeen spending hardly any time in the middle throughout a five-match series. It's important we make the most of these four days and take as much from them as we can."

Meanwhile the England squad have had their security increased following more disturbances in Colombo. While all involved have been advised to avoid demonstrations or political gatherings - they were probably fairly unlikely to attend any anyway - there are no plans to change their schedule. A large demonstration is expected within a few hundred metres of the team hotel on Tuesday. The squad management remains in close contact with the British High Commission.