A dogged Ramkumar Ramanathan battled past a fighting Brayden Schnur in a gruelling four-setter to give India a 1-0 lead over Canada on day one of the Davis Cup World Group Play-off tie, here.

The 22-year-old Ramkumar, ranked 154, outlasted the impressive debutant 5-7 7-6(4) 7-5 7-5 in the first singles, which lasted three hours and 16 minutes.

The Chennai lad thus remains unbeaten in the Davis Cup in 2017 season, having won all five matches he has played.

Yuki Bhambri will now take on World No.51 Denis Shapovalov in the second singles.

A powerful serve was the most potent weapon for Ramkumar but lack of pace in his strokes often made him vulnerable, of which Schnur took advantage many a times in the contest.

Ramkumar wriggled out of crunch situations with his gritty serving and saved as many as 15 of the 18 breakpoints which indeed titled the energy-sapping match in his favour.

More often than not, the Indian served wide and deep to the left of the Schnur, making the returns difficult, which helped him open the court for easy winners.

Schnur, on the other hand, packed a lot of power in his ground strokes and was very impressive with his swift movement and court coverage.

But the 202-ranked Canadian was hit by a crisis of confidence when Ramkumar won the second set pulled away with the third set. Schnur looked down and out, trailing by two sets to one, and down by a break in the fourth set but found energy to fight when Ramkumar dropped serve immediately.

The fourth set was littered with breaks but eventually Ramkumar sealed the match with a backhand winner, again well set up with a quality service.

In a strong start, Ramkumar lost only one point in his first three service games. He mixed his serve nicely and also charged the net when he usually stays on baseline.

Ramkumar faced the heat in the seventh game as he faced two breakpoints but saved both. There were long rallies in which Schnur consistently hit on the backhand of the Indian.

Two unforced errors put Ramkumar down by first breakpoint and he saved it with a deep serve on the left of Schnur and buried the return with a volley winner.

Schnur kept the pressure and picked a low volley to put it out of reach of Ramkumar to earn his second break chance.

Ramkumar saved again with a booming serve and closed the game with an ace.

Schnur’s returns were much stronger than Ramkumar, who lost his serve in the 11th game when he buried an easy volley to net at 15-30 and the Canadian converted the first of the two break points with an overhead smash.

Schnur took the set with an easy hold as Ramkumar sent a return long after 42 minutes of intense tennis.

The Indian continued to face the heat as he saved as many as five breakpoints — two in game one and three in the ninth — but saved all of them to deny Schnur build on the advantage of one-set lead.

Eventually, Ramkumar brought it to even keel by taking the set in tie-breaker. At 3-3, Schnur served a double fault after which Ramkumar served deep on the left of Schnur and smashed a winner in the open court to make it 5-3.

Soon Ramkumar had three opportunities to close the set and he converted the second when Schnur hit a forehand return long.

There was engrossing fight in the third set too. Ramkumar rescued himself amazingly by saving as many as set four set points in the 10th game and broke his rival in the next.

He served out the set love by placing a backhand winner on the right of Schnur, taking a 2-1 lead.

Schnur, to his credit fought well even in fourth set but Ramkumar’s experience helped him clinch the issue.