Middlesex 195 and 133 for 3 (Robson 101*) drew with Nottinghamshire 415 and 295 for 5 dec (Mullaney 100*, Clarke 66*, Fletcher 51)
Sam Robson's second successive century, combined with an afternoon downpour, denied Nottinghamshire top spot in LV= Insurance County Championship Division Two as Middlesex salvaged a draw at Lord's.
Robson's resolute knock of 101 not out, supported by an even grittier unbeaten 18 from Max Holden, thwarted Nottinghamshire's bowlers as they pressed for the victory that would have lifted them above their hosts at the summit.
The Middlesex pair shared an unbroken fourth-wicket stand of 101 to steer their side to 133 for three - chasing a nominal target of 516 - before rain wiped out Nottinghamshire's hopes of forcing a third consecutive Championship win.
The contest was eventually abandoned just before 5pm, leaving the visitors ruing their decision not to make Middlesex follow on after dismissing them for 195 first time around.
Survival had effectively been the aim for the Seaxes ever since day two and Robson and Holden dug in again after resuming at 69 for three, adding only three runs in the first six overs.
Holden had already been at the crease for more than two hours before he progressed into double figures but, although Stuart Broad beat the bat a number of times, the pair managed to see off his initial spell.
James Pattinson looked the most dangerous of the Nottinghamshire seamers, unleashing a ball that reared up at Robson and brushed his glove, only to drop just short of Ben Duckett at second slip.
Robson fended off another rising delivery from Pattinson through the vacant third slip area to advance to 96 - and he leg-glanced the next one to the boundary as well, bringing up his hundred from 177 balls.
Broad switched to the Pavilion End for a second spell, but the Test paceman was barely into his rhythm when rain arrived and the players left the field at 12.30pm, with the situation never improving sufficiently for them to return.