An unbeaten century stand for the sixth wicket by Ravichandran Ashwin and Wriddhiman Saha put India in a respectable position after the first day of the third Test against West Indies in St Lucia on Tuesday.

The visitors were 234 for five at the close of play with all-rounder Ashwin on 75 and wicketkeeper Saha on 46, the pair having added 108 to leave honours even at the Darren Sammy Stadium in Gros Islet.

Opener Lokesh Rahul chipped in with a brisk 50 earlier but India's batsmen were otherwise bogged down until Ashwin and Saha cut loose against the second new ball, plundering 46 runs off the final nine overs.

The late flurry took the gloss off what had been an encouraging day for West Indies after the hosts won the toss and decided to bowl.

Teenage paceman Alzarri Joseph enjoyed a dream debut, in his third over claiming the prized wicket of India captain Virat Kohli, caught at first slip for three.

Joseph (2-38) also snared Rohit Sharma, caught behind for nine, while all-rounder Roston Chase continued his excellent series by picking up two wickets with his off spin.

Fast bowler Shannon Gabriel (1-68) was expensive although he at least took the first wicket of the day when Shikhar Dhawan (one) gloved a short ball down the leg side to wicketkeeper Shane Dowrich.

Jason Holder and Miguel Cummins bowled with discipline in the four-pronged pace attack but went wicketless.

The day belonged to Ashwin, who was dropped on 21 and received another reprieve on 35 when he was caught at point off a Gabriel back foot no-ball.

Ashwin has been a thorn in West Indies' side the entire series, making a century and claiming seven wickets in the first Test before picking up another six victims in the second match.

Rahul followed up his 158 from the second Test by reaching his half-century in 64 balls before falling to the very next delivery when he flicked Chase straight into the waiting hands of short fine leg.

"I wanted to attack the bowlers and put them under pressure because the wicket was a little damp the first hour," said Rahul.

"The ball was doing a bit with sideways movement ... and with this being an open ground, and with the breeze, there was swing throughout the day.

"I did my job pretty well, got the team off to a decent start and the boys carried on from there. We're pretty happy with our effort at the end of the day."

India lead the four-Test series 1-0.