Buchina broke back to 2-1 in the next game, but Watson went on to establish complete control, seizing victory with a bigforehand to the Russian's backhand, which Buchina could only net.
Jankovic showed her class to move ahead with two aces in a row but Robson thrilled the home crowd by fending off two match points with a heavy serve and a bigforehand.
The crowd were willing Williams on but sadly her inconsistency proved decisive in the next game, as two big serves were followed by two double-faults and a wide forehand that allowed the world number four to close out a dramatic victory.