Liam Patterson-White hit 48 and put on a stand of 53 with Fergus O’Neill as Nottinghamshire sensed a chance to push for a final-day win over Hampshire.
Despite the match’s ongoing battle with the weather, with day three again curtailed early, the visitors established a first-innings lead of 15 before reducing Hampshire to 82-4 at stumps.
That gives the hosts an advantage of 67, and with only six wickets remaining before Notts can begin a chase, hopes will be high of forcing a win with a full day left.
Sonny Baker and Kyle Abbott provided the visitors with a stern test, with the former claiming 5/45, but it was one they rose to as Patterson-White and O’Neill pushed the total past 200.
The former’s innings came off 74 balls in almost two hours of dogged resistance, with the partnership for the eighth wicket between the pair coming in 16.2 overs.
It helped the Green and Golds establish a crucial lead and recover from the earlier pressure they had been placed under, with Patterson-White striking four to nudge them in front.
Although Baker completed his five-for by removing Patterson-White to bring the innings to a close, taking the lead had put Notts’ tails up, and O’Neill roared in to take two early scalps.
A wobble-seamer pinned Toby Albert lbw for five - whose dismissal and score were identical to the first innings - before having Fletcha Middleton caught behind by Kyle Verreynne for six as he returned typically-economical figures of 2/19 from 11 overs.
In between, Olly Stone backed the Australian up by seeing Nick Gubbins also taken by Verreynne behind the stumps for 11, and at 30-3, Hampshire were in deep trouble.
O’Neill’s compatriot Jake Lehmann, with Tom Prest for company, helped the hosts battle back with a stand of 43, during which another hour was lost to some passing precipitation.
However, the rain delay clouded over Prest’s thinking, as shortly after the resumption, he aimed a wild pull at Lyndon James and was snaffled by Stone at fine leg for 18 to end the stand.
Captain Ben Brown accompanied Lehmann, who remains unbeaten on 30, to stumps, but with the hosts’ lead still only in double figures, opportunity awaits on the final day.

