In injury time, Lampard did add the fifth, heading in after Drogba had nodded down Cole's high left-wing cross to give Chelsea the added bonus of drawing level on goal difference with Manchester United.
Twelvetrees hit back immediately with his try, after Van Gisbergen missed a tackle, and Croft capped an imperious first-half performance with a try of his own moments before the interval to give the Tigers a bonus point.