Fast bowlers Vishwa Fernando and Asitha Fernando, and left-arm wristspinner Lakshan Sandakan have been flown in from Sri Lanka A's tour of England to the national squad for the first Test against Australia.

With so many frontline Test bowlers currently unavailable due to injury, Sri Lanka's selectors have been forced to look to the next tier of players for replacements. The three bowlers - all of whom are uncapped - have been in form in recent months, either for the A team, or in domestic cricket.

Also flown in from England is batsman Roshen Silva, whose consistency has long made him a Test prospect. Dhananjaya de Silva, who has made ODI and T20 international debuts, and had been in the national team's Test squad to England, has also been named. There is no place, however, for allrounder Milinda Siriwardana, despite him having made an encouraging start to his Test career so far.

At 18, Asitha Fernando is by a distance the youngest member of the squad, and has only played two first-class matches so far - both of them against Pakistan A, in England. He took eight wickets at an average of 23 in those matches, and had bowled Sri Lanka A to a tight victory in the first game, in Leicester, taking 5 for 33 in the final innings of that game. He was also a part of Sri Lanka's side for the Under-19 World Cup earlier this year.

Left-armer Vishwa Fernando, 24, had been in Sri Lanka's Test squads to the UAE and Bangladesh in 2014, but had largely been overlooked since then. He now returns having taken a five-wicket haul in the first-class match against Durham in late June, before taking seven wickets across two games against Pakistan A.

Sandakan, 25, took five wickets in a List A match against Derbyshire earlier this month, and has also been one of domestic cricket's most consistent wicket-takers over the past three years. He was the most successful bowler in the 2015-16 Premier League Tournament, claiming 52 scalps at an average of 23.19 for Colombo Cricket Club. He had also topped the wicket-taking charts in 2014 - the same year he made it to a Sri Lanka one-day squad, though he did not play a game.

Roshen Silva, 27, had also been impressive in the first-class tournament, hitting 678 runs at 56.5, but his selection has been spurred by his recent scores for Sri Lanka A. He recently hit a century and an unbeaten 43 in a first-class match against Durham, and followed it up with scores of 48, 17, 57 and 40 in the first-class games against Pakistan A.

Siriwardana's half century in the first-innings of the Australians' practice match in Colombo was not enough to see him retain a place in the Test squad. He had been particularly impressive with the bat in New Zealand, and has taken 11 Test wickets at 23.36 - even winning the man-of-the-match award in his second Test - and yet has dropped out of favour with the selectors.

Siriwardana's absence, as well as the omissions of Lahiru Thirimanne and Dasun Shanaka, means one of Roshen Silva or Dhananjaya de Silva looks likely to debut in Pallekele. Elsewhere, the same top order that played in the Lord's Test is likely to take the field again.

Nuwan Pradeep and Suranga Lakmal provide some leadership to the fast-bowling battery, in the absence of Dhammika Prasad, Dushmantha Chameera and the suspended Shaminda Eranga. Rangana Herath is likely to be the first-choice spinner, and Sandakan will have to edge offspinner Dilruwan Perera out of contention if he is to debut in Pallekele.

With both Dinesh Chandimal and Kusal Perera in the squad, and probably in the XI, Sri Lanka have to make a choice as to who will keep wickets.

Andrew Fidel Fernando is ESPNcricinfo's Sri Lanka correspondent. @andrewffernando