David Willey is wary of 'dangerous' Northants as the England star prepares to clash with his former county on Thursday (start time 2pm).
The Steelbacks travel to Headingley for the final match of this season's Royal London One-Day Cup North Group.
David Ripley's men have won just two of their seven 50-over games so far, meaning they will not make the knock-out stages.
But Yorkshire can, and they know they need to beat Northants to keep their hopes of qualification alive.
The Steelbacks are missing several key players, including Josh Cobb and Richard Levi, but Willey knows just what the county he was raised at can do in limited overs cricket.
“In one-day cricket, Northants are a dangerous side,” Northampton-born Willey said.
“They’ve got lads who can hit the ball to all corners. If they come off, we’ll be under pressure.
“They’re out of the competition, which can be dangerous at times.
“We need to be on our A game and play well.
"It’s no good beating Lancs, turning up and then thinking it’s going to be easy. If we do, we’ll come up short.”
Willey was the star of the show in Tuesday's win against Lancashire, smashing a sensational 131 before taking four for 59 to seal the win with the ball.
And the 28-year-old, who was Northants' hero in the T20 final victory against Surrey in 2013, said: “As days come on the cricket calendar, it was a pretty good one.
“It’s nice to get an opportunity to bat towards the top.
“It’s something I’ve done before at Northants with decent success and like doing.
“I missed out at Derby, and it took me a while to get going at Lancs. But I knew that it was a good pitch and could catch up if I needed.
“Towards the back end of my time at Northants I did it, but I’ve not done it at all up here.
“They asked me if I fancied it, and I said ‘absolutely’.”
England Test captain Joe Root returns to Yorkshire's 13-man squad for crunch match against the Steelbacks, who have mixed things up ahead of Saturday's return to County Championship Division Two action at home to Leicestershire.
Ben Cotton and Charlie Thurston are in line to make their first Northants appearances.
Yorkshire's 13-man squad: Ballance, Bresnan, Carver, Fisher, Kohler-Cadmore, Lyth, Patterson (c), Plunkett, Pujara, Rashid, Root, Tattersall (wk), Willey.
Steelbacks' 13-man squad: Newton, Vasconcelos, Kleinveldt, White, Duckett, Hutton, Wakely (c), Cotton, Thurston, Rossington (wk), Keogh, Sanderson, Zaib.