The England A paceman was forced out of the NatWest defeat by Sussex at Hove on Wednesday by a nasty-looking side injury.
It is actually a problem with his inter-costal muscle which seems certain to keep him out for at least two weeks, and the Championship and Sunday games against Sussex and Hampshire.
Wednesday was Chapple's first game back from a separate stomach muscle problem which ruled him out of the victory over Middlesex at Uxbridge.
And he played no part in Lancashire's Benson and Hedges Cup qualifying campaign earlier in the season after suffering a dislocated knuckle fielding in the opening game against Yorkshire.
Chapple's latest injury will leave Lancashire relying on Peter Martin and Darren Shadford to lead their pace attack, with Wasim Akram also missing and Richard Green still struggling with his achilles problem.
Green is playing in the current second team game against Kent at Haslingden, but only as a batsman.
And that's all Lancashire have needed as left arm spinner Gary Keedy claimed 7-74 yesterday to put them in a strong position.
Kent were all out for 204 in reply to Lancashire's 365-7 declared despite 77 from Cambridge University student Ed Smith.
Lancashire then extended their lead to 366 with Mark Harvey following his first innings 92 with another half century.