George Bailey struck a brilliant 161 to hammer home Hampshire’s advantage on day two of their County Championship division one clash with Surrey at the Oval.
The Aussie shared stands of 167 with Sean Ervine (83) and 72 with Ian Holland (58 not out) before the visitors declared on 648 for seven.
Surrey reached 113 for one by stumps on the second day – as they began their reply to the mammoth total.
Michael Di Venuto has challenged his troops to scrap for a draw over the next two days.
But the Surrey head coach insisted it is Hampshire’s victory to lose, with the wicket likely to deteriorate as the game goes on.
He said: ‘It was a tough day with the ball.
‘It’s a batting wicket and there were some set batters in there, so it was pretty hard to contain.
‘We responded well with the bat. It was important we bounced back at the end there.
‘Hampshire have had the best of the batting conditions, though.
‘And I expect the wicket will deteriorate over the next two days.
‘The job is there for us to do and come out of the game with a draw. It’s up to everyone to step up now.’
Hampshire resumed on 361 for four and produced a dominant first session, which yielded 136 runs.
By the time Ervine became the first wicket of the second day’s play, he and Bailey had taken the score to 528.
Ervine’s 123-ball 83 included eight fours and one maximum, as the visitors hammered home their advantage.
Bailey went on to reach 161 before he was sixth out – caught at long-on in the pursuit of more quick runs.
His 294-ball knock featured 15 fours and two sixes and put Hampshire in an almost unassailable position.
Meanwhile, Ian Holland cruised to his maiden first-class half-century as the Ageas Bowl outfit piled on the runs against the toiling Surrey attack.
And he was unbeaten on 58 when the declaration finally came – in the wake of Gareth Berg’s dismissal for 35 off just 16 deliveries.
Hampshire’s quest for glory from here on will not be easy, though.
They will aim to bat once in the game but Surrey wasted no time in showing their fighting spirit by reaching 113 for one at the close on day two.
Mark Stoneman was the only wicket to fall after he had notched 57.
The one-time Hampshire target had put on an opening stand of 103 with Rory Burns (45 not out) before nicking Ervine to Rilee Rossouw at first slip.
Surrey will resume this morning still 535 runs adrift.
With Di Venuto expecting the wicket at the Oval to deteriorate over the final two days, much of Hampshire’s hopes could depend on the talents of young leg-spinner Mason Crane.
Back from international duty, he will have a major part to play in bowling the hosts out twice.