Davenport was not the only seed to encounter trouble, the fourth-seeded Amanda Coetzer of South Africa salvaging a match point in the third set before subduing Lisa Raymond, 4-6, 6-4, 7-5.
Davenport, who was playing in her first tournament since winning Wimbledon three weeks ago, looked rusty for much of the match. Her normally razor- sharp groundstrokes frequently flew long and she was unable to keep the fleet Rubin on the move.
"She hits the ball really hard," Rubin said, "and if you feed it right to her and she doesn't have to move, it's trouble."
Davenport said: "It was a tough match. I didn't play great. She played very well and I played a little sloppy. She was hitting some great shots and put the pressure on me to play better. I needed to put some more first serves in and get on her and I did that more in the third set."
The Swiss player Patty Schnyder scored her most impressive win since March, beating Russia's Elena Likhovsteva 6-3, 7-5.Reuse content