It leaves a three-way battle for the championship heading into the final round of fixtures following Yorkshire's defeat to Somerset inside three day at Headingley yesterday.
Middlesex head into the end of season title showdown with a nine-point cushion over the White Rose, while third-placed Somerset can still leapfrog the pair if the match finishes drawn.
Yorkshire had arch rivals Lancashire to thank for batting out a draw in the rain-affected match against Middlesex at Old Trafford.
Middlesex declared on 240/8 soon into the afternoon session and gave themselves 40 overs to bowl Lancashire out, with a target of 309 on offer.
England wicket-keeper Jos Buttler led an early charge for the Red Rose.
But once he departed off Steven Finn's bowling, Lancashire were content to bat out for a share of the points and the captains shook hands after 26 overs, with the hosts on 80/1.
Somerset moved to within one of the White Rose and host relegated basement boys Nottinghamshire at Taunton next week.