Kolkata, Jun 28 (IANS): Former Davis Cup winner and India's non-playing captain Jaidip Mukherjea on Wednesday lavished praise on India's top singles player Ramkumar Ramanathan, saying his victory over world No 8 Dominic Thiem is a great achievement.

Ramanathan, ranked 222nd, on Tuesday pulled off a straight set upset over Thiem in the pre-quarterfinals of the Antalya Open in Turkey.

In a 6-3, 6-2 verdict, the strapping Indian fixed a date with Cyprus star Marcos Baghdatis in the quarter-final, shocking the tennis world and sending social media into a tizzy.

"It's a great achievement. I remember Leander beating Sampras and how big that was. But in recent years, Ramanathan's win has to be right up there," city-based Mukherjea told IANS over phone from Singapore.

Paes had pulled off one of the biggest upsets in Indian in men's singles when he beat then world number one Pete Sampras in straight sets at the Pilot Pen International Tennis Championships in 1998. Paes had himself called it his biggest achievement.

On Tuesday, Ramanathan, after beating Thiem, a French Open semi-finalist who beat World No 4 Novak Djokovic in the quarters, had said: "I thank the crowd for coming out and cheering. I like the grass courts. Courts are fast. I took my chances and it worked out. I worked really hard for this win."

Ramkumar hit 10 aces and converted three break points, while Thiem only had one chance to break the Indian, which he failed to convert.

"Now he needs to work on his backhand and most importantly stay grounded. He is a very hardworking guy and is very dedicated. He needs to improve his fitness also for a longer run," Mukherjea, who represented India in Davis Cup for 13, featuring in 97 rubbers in 43 ties, added.