He and Martin-Jenkins extended their sixth-wicket partnership to 171, and when Lewry struck twice in his first two overs Lancashire were on the ropes, but Law and Cross ensured the race for the title remains intriguingly poised.
Kaushalya Weeraratne hit a mammoth six onto the adjacent moto-cross track, but that proved to be the final boundary for Sri Lanka, as the final four overs produced only 18 runs.