Already assured of a place in the semifinals, Mahesh Bhupathi and Mark Knowles finished their group engagements in the World tour Finals with a straight set defeat against defending champions Danie Nestor and Nenad Zimonjic here on Thursday.

The third seed Indo-Bahamin pair lost their last group B match 4-6 6-7(9) to the top seeded Canadian-Serbian duo after battling for one hour and 18 minutes.

This was first win for Nestor and Zimonjic in the season-ending prestigious tournament and they failed to graduate to the next stage.

Bhupathi and Knowles had won their first two matches to secure a place in the semifinal stage.

Bhupathi was hopeful to make the summit clash. "We have to look after ourselves and our games. If we execute like we have been the last three matches, I think we'll have a good shot to win on Saturday," the Indian tennis star said.