Americans Bob and Mike Bryan stood one match away from ending the season ranked on top of the world as they reached the doubles final at the ATP World Tour Finals with a 6-4, 6-4 win over Mahesh Bhupathi and Mark Knowles.
The second seeds will usurp Daniel Nestor and Nenad Zimonjic as world number ones if they beat Max Mirnyi and Andy Ram in the showpiece match on Sunday.
"It's going to make for a huge occasion. It's going to be a special feeling walking out there, competing at our hardest," Mike Bryan told reporters on Saturday as he looked forward to playing in front of 17,500 fans at the O2 Arena.
"It's going to be so loud tomorrow, it's going to be a big final, packed house. No better place to play than out here."
Belarussian Mirnyi and Israeli Ram beat Frantisek Cermak and Michal Mertinak 6-4, 7-6 in the other semi-final.