Ryan McLaren underlined the need for Hampshire to establish a first innings lead at Chester-le-Street and insisted: A big partnership is crucial.
The debutant took four for 60 as his new side bowled Durham out for 213 in the County Championship division one clash.
In seamer-friendly conditions at the Test venue, McLaren, 32, was impressive with the new ball before returning to polish off the home side’s tail.
However, Hampshire then stuttered to 47 for three before reaching 77 for no further loss at stumps.
The former South Africa international knows how crucial a first-innings lead will be to the visitors, who need to win to boost their hopes of escaping the drop.
And with ex-Durham skipper Will Smith (22 not out) and Liam Dawson (13 not out) set to resume this morning, he is hoping his new team-mates can take control of the game.
McLaren, who is delighted to be back in the English game after stints at Kent and Middlesex, said: ‘I have always enjoyed playing county cricket and when the opportunity came I was only too happy to take it.
‘Hampshire are a nice bunch of guys and there’s a lot to play for in trying to help them stay up.
‘I haven’t played a lot in the last few months and Durham is not a bad place to start.
‘It could have been somewhere like Taunton!
‘I was happy with the way the ball came out. The match is evenly-poised, so a big partnership is crucial for us now.’
Ryan Pringle, who was dropped by Smith at gully on 27, dominated the Durham innings with 99 after going in at 65 for five.
The decision to bat looked flawed when the difficulties were underlined by Scott Borthwick facing 57 balls to score nine.
Although Hampshire handed a debut to Ryan Stevenson, from Devon, it was his experienced team-mates who did the damage.
Gareth Berg took three for 27 and Fidel Edwards three for 57 as the home side were dismissed in 63.1 overs.
When Hampshire batted, Jimmy Adams cut the first ball he faced for four only to lose his off stump to the next delivery.
Onions then had James Vince dropped on nought by Gordon Muchall at third slip.
A few overs later, though, Vince, playing back, seemed to be surprised by extra bounce and was caught low down by Pringle at gully for nine.
Muchall then sensationally atoned for his earlier miss when he dived to his left at third slip to hold a one-handed catch when Michael Carberry drove at an away swinger from former England international Onions (three for 32).
But Smith dug in alongside Dawson to ensure Hampshire reached the close of play with no further damage.