Mark Stoneman, Sam Robson pile up record opening stand worth 376 at Hove

Mark Stoneman and Sam Robson broke Middlesex's record for the highest first-wicket partnership as they put Sussex's toothless attack to the sword.

Robson was unbeaten on 192 and Stoneman made 174 as Middlesex piled up 400 for 2 on the first day of the LV= Insurance County Championship Division Three match at Hove. They beat the 372 by Mike Gatting and Justin Langer against Essex at Southgate in 1998 and when Stoneman was eventually dismissed on 376, they had compiled the third-highest partnership for any wicket in Middlesex's history.

The second new ball brought Sussex a breakthrough when Stoneman was caught behind for 174 in the 86th over, his first hundred since his move from Surrey. But Robson ploughed on and by stumps had faced 285 balls and hit 23 fours. He walked off to a standing ovation and will have the third double-hundred of his career in his sights on Tuesday.

It was a good toss to win with the sun out and the pitch offering little assistance but apart from one chance Robson offered on 61, when he was dropped by wicketkeeper Oli Carter, the Middlesex pair made untroubled progress.

Sussex employed seven bowlers, although George Garton was not used, but their attack was neutered by a benign surface and the unfussy way Stoneman and Robson accumulated their runs. They had 134 on the board at lunch, the highlight of the morning session when Stoneman carved Dan Ibrahim through the off side for three successive boundaries.

There was a feeling that Sussex would pay a heavy price when Carter reprieved Robson shortly after lunch off left-armer Sean Hunt and even a change of ball in the 40th over didn't offer any respite for the hosts.

Stoneman drove Delray Rawlins through the covers to reach his hundred first and Robson followed shortly afterwards with a boundary off Crocombe. They added 154 runs in the afternoon session and Robson needed only 55 more balls to move to 150.

When the partnership went past 338 it was the highest Sussex have conceded against Middlesex, beating a record which had been set by Robert Lucas and Tim O'Brien back in 1895, 126 years ago.

Eventually Stoneman played a tired shot at Crocombe, and this time Carter held on. The former Durham left-hander had faced 266 balls and hit 20 fours and two sixes. Hunt then picked up belated reward when Steve Eskinazi was caught behind pushing forward just before stumps, but it was a chastening day for Sussex's young attack.