India's World Group hopes are hanging by a slender thread as its top singles player, Somdev Devvarman is still doubtful to play Sunday's reverse singles in the play-off tie against Japan due to a shoulder injury.

India are afloat in the tie with Mahesh Bhupathi and Rohan Bopanna on Saturday, winning the doubles rubber against Yuichi Sugita and Tatsuma Ito.

Somdev is scheduled to play the first reverse singles against Kei Nishikori tomorrow and if he misses the tie, Vishnu Vardhan will have to play the must-win tie.

Somdev, whose injury flared up during Friday's opening singles match against Sugita, had undergone an MRI and the extent of the injury is still unknown since the reports have not come as yet.

"We are still waiting and I will be able to decide only after seeing the reports. He had inflammation and pain which affected his performance against Sugita. He could not play aggressively," India's non-playing captain S P Misra said.

"An unfit Somdev against a player with the ability of Nishikori makes it tough for India."

Talking about the tough doubles rubber on Saturday, Misra complimented the Japanese players for their strong showing but said his boys played better.

"They were charged up. They were 2-0 up and nothing to lose. They played decently well and took chances. We were slightly better.

"Moreover Bopanna had to adjust to the right court. Bhupathi is always a left-court player so Bopanna had to play there. Leander is the only player we have who plays on right court. When you have to make that adjustment, the co-ordination and understanding becomes a bit difficult."

Bhupathi also praised the Japanese players and said he and Bopanna had to bring out the best to win the doubles tie.

"We found a way to complement each other today. It got a bit dicey at the end, but we got the job done. Their strengths are their return and second shots," he said.

Bopanna, World No. 14 in doubles, was also impressed with Ito and Sugita, who are not even inside top-450.

"In the Davis Cup, the rankings don't matter. They had nothing to lose. They played at a high level."

Bopanna was hopeful that Somdev would play and win the rubber against Nishikori.

"We are hoping Somdev comes out and gives us the win. I am looking forward to it."