Yeltsin is supposed to arrive after the three-day head-banging session finishes for a brief session with his Western counterparts about how Russia is getting on with its economic reforms.
The trouble is, some say, that if Mr Yeltsin - a consummate strategist - arrives before time, he will grab the limelight and the summiteers' other deliberations on the world economy and the developing world will be ignored.
These fears, however, are probably unfounded. The Russian president, who has stepped up his campaign for Western aid, is famous for suddenly disappearing when key appointments loom (a sudden illness or a pressing need to visit the Black Sea coast). A surprising appearance would be a new departure.