Bengaluru, Feb 14 : India's Ramkumar Ramanathan fought back impressively after losing the opening set to upset top seed Luca Nardi of Italy to reach the singles quarterfinals of the Bengaluru Open here at the Karnataka State Lawn Tennis Association (KSLTA) Stadium on Wednesday.

Ramkumar, who has been given a wild card for this tournament, looked down and out after the opening set but banked on his big serves to beat Nardi 1-6, 6-4, 6-4 in an hour and 33 minutes in the second-round clash at Centre Court.

In the day's other matches, Maks Kasnikowski of Poland upset fourth seed Benjamin Bonzi of France 6-3, 6-4 in the second round while another Indian SD Prajwal Dev suffered a 3-6, 0-6 loss against fifth seed Adam Walton of Australia in a first-round encounter.

The prestigious ATP Challenger event is being organised by Karnataka State Lawn Tennis Association with the final scheduled on Sunday.

Earlier, Ramkumar kept his nerves when things were not going his way to register the biggest upset of the day.

In the opening set, Ramkumar struggled to find his serving rhythm and that also affected his returning ability as Nardi raced through.

However, the big serving Indian regrouped at the start of the second set and won 93% first serve points and never even faced a break point in the set. In contrast, Nardi's serve was put under regular pressure to take the match in the decider.

The final set followed a similar pattern with Ramkumar coming up with five aces and even raising his second serve percentage to wrap up the match.

He will now face the winner of the match between ninth seed Seongchan Hong of South Korea and Russian qualifier Alexey Zakharov.

/IANS