Calcutta: The third spinner's slot will be a matter of much debate when the national selectors meet in New Delhi on Thursday to pick the squad for the three-Test series in Sri Lanka, starting August 12.

Barring this one aspect, Sandeep Patil and Co. would have very little to fret about while choosing the squad, where at least 13 players will automatically select themselves.

Harbhajan Singh has justified his recall with decent outings in Bangladesh and in the one-dayers in Zimbabwe, and is set to be given a full series, while Ravichandran Ashwin, too, is ready to roll in what would be his maiden Test series in Sri Lanka. With two spots locked in the XI, the selectors will have to decide on the third spinner's slot.

Karn Sharma, who was the third spinner in the Test squad in Bangladesh, got injured ahead of the Zimbabwe tour.

There was no official update on his injury status though there was talk that he has recovered. Still, Karn is not assured of a spot even though Ravindra Jadeja has fallen out of the selectors' good books in recent months.

Akshar Patel, considered to be a replacement for Jadeja, has put in consistent performances in limited-overs matches. Also, the fact that Amit Mishra and Pragyan Ojha have been rewarded with India A call-ups indicate that they have not written the pair off completely. Interestingly, it was Mishra and Pragyan who shouldered the responsibility in India's last Test series in Sri Lanka, in 2010, when Harbhajan returned home after the first Test.

The six specialist batsmen who are automatic choices are openers Murali Vijay and Shikhar Dhawan, captain Virat Kohli, Ajinkya Rahane, Rohit Sharma and A team captain Cheteshwar Pujara. Young Lokesh Rahul, who missed out against Bangladesh due to illness, is likely to make a comeback.

Wriddhiman Saha is another automatic selection as first-choice wicketkeeper. It will be interesting to see if the selectors include an additional wicketkeeper as 16th member. In such a scenario, the choice will be between Naman Ojha and Sanju Samson.

Mahendra Singh Dhoni's Test retirement will give Saha, who was the former's understudy in Sri Lanka in 2010, his first full series behind the wickets. Naman, in the Test squad for the final match against England last year, was also there in Australia till the first Test, as Dhoni had missed out with an injury.

The three pacers likely to make the cut are Umesh Yadav, Ishant Sharma and Bhuvneshwar Kumar. Varun Aaron is also likely to be included.