Centurions put Durham in control
A second-wicket partnership of 274 from Mark Stoneman and Scott Borthwick ensured home side Durham got the better of Middlesex on day one.
The home side reached 411 for four at the close and will attempt to build on an already commanding total when play resumes in the County Championship Division One clash on Monday morning.
Their innings was anchored by Stoneman's entertaining 187 before Borthwick assumed responsibility with an equally impressive unbeaten 164. Their partnership was Durham's highest ever for the second wicket in first-class cricket.
Middlesex won the toss and elected to field and it was a decision that away captain Chris Rogers no doubt rued as his bowlers were made to toil on the opening day.
Stoneman took just 47 balls to bring up his half-century and he and Keaton Jennings took the score to 82 before Toby Roland-Jones bowled Jennings on 16 to end his 41-ball innings.
Borthwick replaced Jennings at the crease and he was initially happy to play second fiddle as Stoneman dispatched the ball to the ropes regularly.
The home side passed 100 in just the 20th over and Stoneman and Borthwick guided them to 140 for one at lunch before they went from strength to strength after the interval.
Two fours off the bowling of Neil Dexter in the 27th over saw Stoneman enter the 90s and he brought up his 100 five overs later with a leg glance for four off Roland-Jones, his 17th boundary from 105 balls.
Stoneman had a reprieve when he was dropped by wicketkeeper John Simpson in the 38th over as he misjudged a Tim Murtagh delivery.
Borthwick brought up his 50 an over later, dispatching Finn to the boundary. His half-century took 71 balls and included eight fours and a six.
Borthwick then pulled Steven Finn away to the ropes for four to take the score past 200 in the 41st over and seven overs later his and Stoneman's partnership passed 150 when Borthwick nudged a single off the bowling of Ravi Patel.
Stoneman passed his previous best for Durham - 131 against Yorkshire earlier in the season - when he took two runs off Paul Stirling's bowling in the 51st over as Durham went to 237 for one.
The 250 was brought up just four overs later as Borthwick clipped a single off Stirling - whose spin had been causing the batsmen a few problems.
Stirling was certainly halting Durham's speedy scoring but he could not prevent Stoneman from reaching 150 in the 61st over with a single.
Three balls later and Borthwick was jumping for joy in the sunshine as a delightful on-drive to the ropes saw him reach triple figures from 132 deliveries.
Durham reached tea on 286 for one shortly after Stoneman and Borthwick's partnership passed 200.
Borthwick flicked a single off his pads down to long leg to bring up the 300 team total and he and Stoneman guided Durham to 356 before the latter's exquisite innings was finally brought to an end on 187 when he was caught at leg slip by Sam Robson off Stirling.
Stoneman's stay at the crease lasted 249 balls and included 26 fours.
Middlesex claimed their third wicket of the day when a mix-up with Borthwick saw Michael Richardson run out by Rogers for four.
With Ben Stokes joining the action, Borthwick shrugged off Richardson's dismissal to pass 150 by pulling a short Roland-Jones delivery to the fence for four.
A Stokes thick edge evaded those behind the wicket and flew down to the third man boundary to bring up 400 before he perished on 23 as Finn found away through his defences.
But Middlesex's bowlers could not get the better of Borthwick and he was unbeaten at the close of play on 164, with nightwatchman Mark Wood on nought.