Jimmy Floyd Hasselbaink opened the scoring for Chelsea with a classy left foot curling shot from the corner of the box after 21 minutes.
Hammers equalised seven minutes from time when Frederic Kanoute hit in a loose ball from seven yards, following a set piece.
Team news:
Gianfranco Zola hopes to regain his starting role for Chelsea. With Celestine Babayaro away on international duty and Mario Melchiot suspended, Albert Ferrer will contest the right-back spot with fit-again William Gallas. Marcel Desailly did not complete Tuesday's training session because of a slight twinge but is expected to line up alongside John Terry at the heart of Chelsea's defence.
Stats:
Chelsea have won their two subsequent Premiership games against Leeds (2-0 at home) and Leicester (3-2 away).
Chelsea have failed to reach the last 16 only once in six seasons. They needed a replay to defeat Norwich in the Third Round, but have won their last three League and Cup matches at home.
Betting:
West Ham 7/4 - Draw 11/5 - Chelsea 11/8
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