Australia went to lunch on day one of the second Ashes Test at 1-73 after being sent in to bat by England, during a session disrupted by protesters and light rain on Wednesday.
England claimed the prized scalp of first-Test hero Usman Khawaja, who made a bad leave on a Josh Tongue delivery on the last ball before lunch to be bowled for 17 - but the session still belonged to Australia.
Warner has been the star, bringing up his 50 when he hooked Tongue for six and going to the break unbeaten on 53.
The opener's half-century is his first in the nine innings since his double-century in the Boxing Day Test, and his second score beyond 50 in his past 20 innings.
It is also the first since the 36-year-old announced his plans to retire in January, with the hope he can hold his place in the side for long enough.
The runs couldn't have come at a more crucial time for Australia, in difficult conditions on a green wicket and either side of a 12-minute rain delay.
Play was also stopped for five minutes when Just Stop Oil protesters charged towards the pitch after the opening over, with players forced to protect the wicket from their orange powder.
Jonny Bairstow caught and carried one protester all the way back to the boundary, while Warner and Ben Stokes helped stop another.
Warner's defence against the Duke's ball has been just as tested.
Several deliveries passed the outside edge of both openers, with the ball moving around and dark clouds overhead.
But when England created chances, the hosts could not take them.
Joe Root grassed a low opportunity when Khawaja was on one off James Anderson, while Ollie Pope put down a more straightforward one off Stuart Broad at fourth slip with Warner on 20.
Beyond that, it has been clear Warner has wanted to unsettle England's bowlers.
He slog-swept Ollie Robinson for four after earlier attempting the same shot off Broad, before later walking down the wicket at the England veteran.
There has been convention mixed around those flashes of modern batting.
Warner got off the mark when he cover-drove James Anderson for four in the first over, and also hit Tongue for two consecutive fours through gully and backward-square before lunch.
Australia's first-session resistance came after Mitchell Starc was brought back into their team for the Test, with the tourists preferring the variety of the left-armer ahead of Scott Boland.
This match looms as crucial in the outcome of the series with Australia a chance to go 2-0 up after their exciting two-wicket win in Birmingham.
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