After beating Durham by 10 runs at Chester-le-Street on Friday Yorkshire followed up with a 12-run victory against Worcestershire at New Road.
The result took them to fourth place in the North Group – level on points with second-placed Lancashire – after three wins from their opening four games.
Worcestershire stay top after four victories from their opening five matches, with both clubs looking a good bet to reach the knockout stages.
On a baking hot day in the West Midlands, with a New Road outfield that is so often flooded by the nearby River Severn looking positively parched, Yorkshire scored 179-7 after being sent into bat.
The visitors were spearheaded by 40 from Gary Ballance, who struck four sixes in a 21-ball innings.
Adam Lyth chipped in with 35 from 21 balls, Harry Brook 33 from 23, and Jonny Tattersall 29 from 21, Pat Brown returning 3-34.
It was a competitive total, but not necessarily a winning one given the pitch, a fast outfield and a temperature nudging 30 degrees.
Not for the first time, however, Yorkshire displayed a facility for closing out a game that might have gone against them, bowling and fielding well to restrict the hosts to 167-8 before a crowd of around 3,500.
Tim Bresnan and Steve Patterson each captured three wickets, Ross Whiteley top-scoring with 37 from 30 balls.
On a day when the PA system was so loud that one half-assumed that it was being soundchecked for an ensuing AC/DC concert – with the matchday announcer more irritating than the fly that stubbornly refused to leave the press box – Yorkshire showed one change to the side that triumphed in the north-east.
Jordan Thompson, a 21-year-old all-rounder, replaced pace bowler Matthew Fisher, who is on England Lions duty at this venue for the next four days against India A.
As is his wont, Lyth got Yorkshire off to a flying start, creaming three boundaries in the opening over from Dillon Pennington.
He followed up by lofting Brown for six before falling to the same bowler when he picked out Ross Whiteley at deep square-leg, having made 35 out of 41 in the fifth over.
Tom Kohler-Cadmore, making his first return to New Road since leaving Worcestershire for Yorkshire last summer, managed only five before he was yorked by Pennington trying to make room to hit through the offside, leaving the visitors 49-2.
Some lofty striking from Ballance and Brook took Yorkshire to 90-2 at the halfway stage, the third wicket falling with the total on 113 in the 12th over when Ballance lofted the part-time spin of Travis Head, the former Yorkshire batsman, to Daryl Mitchell at deep mid-wicket.
Mitchell had Brook caught around the corner by Joe Clarke, and when Jack Leaning skied Luke Wood to Martin Guptill at long-on Yorkshire were 147-5 in the 17th over.
There followed one of the best relay catches one will see when Tattersall launched Brown out to long-on, where Mitchell flicked the ball back on the boundary as his momentum prepared to take him over the rope and Guptill brilliantly claimed the rebound one-handed.
Brown had Bresnan lbw with the next ball, Thompson launching the final delivery of the innings from Ed Barnard for six over wide long on.
When Worcestershire replied Bresnan removed two of their biggest dangers in the first three overs.
First he had Guptill caught behind from the second ball of the innings as the New Zealander tried to carve through the offside and then, in his second over, he had Clarke extremely well caught at mid-off by Patterson after the ball was skied almost as high as the famous cathedral.
Patterson had Mitchell caught around the corner by Jack Brooks to leave the hosts 32-3, and Worcestershire fell to 50-5 when Ben Cox picked out Lyth at long-off off Azeem Rafiq and Head found Ballance on the square-leg boundary, giving Thompson his maiden first-team wicket.
Bresnan claimed his third wicket when captain Brett D’Oliveira was also caught around the corner by Brooks, and the game was as good as dusted when Leaning judged a superb catch running in from deep cover to dismiss Ross Whiteley off Patterson as Worcestershire slipped to 132-7 in the 17th over.
Patterson picked up his third wicket in the penultimate over when Wood holed out to Thompson at deep mid-wicket, and despite an unbeaten 25 from Barnard, Yorkshire sealed a professional win.