Gareth Berg returned to haunt his old county Middlesex with a rapid half-century as Hampshire, 295 for five overnight, were all out for 413 on a rain-hit second day at the Ageas Bowl.
South African-born Berg, released by Middlesex at the end of last season, struck five fours and a six off Ollie Rayner from 75 balls when play resumed in early afternoon after 33 overs had been lost to the weather.
Hampshire soon lost Sean Ervine, bowled playing across the line to Toby Roland-Jones after only adding a single to his overnight seven but then Berg joined Will Smith in a seventh wicket partnership of 91 in 23 overs.
Berg hit Rayner for 14 off three balls on his way to his first 50 for Hampshire until pace bowler Neil Dexter came on and Berg attempted one big hit too many.
In the same over, the 116th of the innings,Smith edged to wicketkeeper John Simpson for 93, an innings containing eleven fours in 191 balls.
Dexter had West Indian Fidel Edwards caught at long-off for a single at 393 but last man James Tomlinson was also severe on spinner Rayner, striking for 14 in three deliveries in helping Hampshire pass the 400 mark in the 128th.
Tomlinson, who had made 17, fell to a catch in the deep by Roland-Jones to give Dexter creditable innings figures of five for 64 but Hampshire's final total was many more anticipated by Middlesex new captain James Franklin when he won the toss and chose to field.