Ashton Agar's stay in India has been extended to take in Australia's major warm-up for the Test series as the possibility grows that he may be in line for an extraordinary international debut in Chennai.

Previously scheduled to depart for India once the full touring squad had assembled, Agar will now be playing the three-day match against India A beginning on Saturday, and may yet have his time on the subcontinent expanded to include the Tests.

Agar is one of three spinners Australia will field in the practice game, Xavier Doherty and Nathan Lyon being the other two. Michael Clarke and David Warner will miss the match, following their recovery from injuries, to be ready for the first Test on February 22.

Only 19 years old and having played just a pair of Sheffield Shield matches for Western Australia following the shoulder injury to Michael Beer that ruled him out of this tour, Agar's left-arm spin has stuck in the memory of all who have witnessed his bowling in recent weeks.

His mature approach and skill in the field and with the bat has notably impressed the national selector John Inverarity, who is en route to India to discuss the composition of the team ahead of the first Test with the captain Michael Clarke and the coach Mickey Arthur.

"The plan at the moment is that he returns in time to play for Western Australia but there is a possibility that he could stay a bit longer," Inverarity told The West Australian. "We needed someone to make up the XI and it was a very good opportunity to invest an opportunity in a promising young player."

Inverarity's panel named numerous spin bowling options for the tour behind the incumbent Test tweaker Nathan Lyon, including the Tasmanian Xavier Doherty and the allrounders Glenn Maxwell and Steve Smith. Agar lost little by comparison to his more experienced slow bowlers when he delivered eight overs during a two-day practice match earlier this week, and now has a further opportunity to usurp his seniors.

"Ash bowled really well in the two-day game," Clarke told AAP. "Everyone knows he's very talented. He's had success for Western Australia [eight wickets at 30.12 in two matches].

"I spent some time with him yesterday in the nets and tried to get him to watch some of the Indian spinners in the nets and see what he was learning from what they were doing. He's going to be a very good bowler. He wants to learn - he wants to get better.

"You never know what could happen. He's very lucky now. He's been given the opportunity to play in this three-dayer. We have Xavier Doherty, we have Nathan Lyon, we have Glenn Maxwell and we have Ashton Agar who all bowl spin. We want to make sure we're doing everything in our power to make the right decision for the first Test."

In this there are parallels with Lyon, who was chosen for Australia's Test side in Sri Lanka in 2011 after only a handful of Sheffield Shield appearances for South Australia, and to date has played more than half his 35 first-class matches at Test level. In the absence of outstanding spin bowling talent bolstered by experience, the selectors have been inclined to flights of fancy, of which Agar would be another.

His spells for the Warriors against New South Wales on his Shield debut at Blacktown Oval were noteworthy against batsmen well versed in tackling spin, the wickets of Scott Henry and Peter Nevill gained through genuine turn and changes of pace.

Agar's Shield batting has also been useful, reaping one half-century and one other handy score in four innings so far. He went to India on the cricket equivalent of an internship, but is now a chance of making a most rapid graduation to full duties.

'I wasn't expecting too much at the start of the summer but it has all happened very quickly and it has turned into a bit of a dream,'' Agar said. ''Michael Beer was bowling really well but he got injured. That gave me an opportunity to play for Western Australia, now to tour India for a week. It has been great.''