Joe Leach picked up three early wickets for Worcestershire before centurions Jonny Bairstow and Andrew Gale figured in a record partnership for champions Yorkshire on the opening day of the LV = County Championship clash at Scarborough.
Leach took his Championship wicket tally for the campaign to 47 as he dismissed Will Rhodes, Alex Lees and Jack Leaning.
Yorkshire were then 57-3 on a greenish pitch after electing to bat – but then Bairstow and Gale took command.
They figured in a stand of 254 in 58.1 overs – a record fourth wicket partnership for Yorkshire against Worcestershire – as the Tykes reached 357-5 off 88 overs.
Bairstow looked in particularly fine form and reached his 100 off 112 balls to press his England claims on the day Alastair Cook's side suffered a 405 run defeat in the second Ashes Test.
He was eventually out for 139 from 183 balls with 18 fours and one six.
But Gale's contribution was equally valuable for the home side and he provided the perfect foil for Bairstow in reaching three figures off 183 deliveries with 11 boundaries.
He finished unbeaten on 127 from 233 balls with 13 fours.
Leach shared the new ball and broke through in his second over when Rhodes (9) was caught at the second attempt by Ross Whiteley at first slip.
The same combination then accounted for Lees (12) with Yorkshire on 33-2.
Leach switched ends and struck again he trapped Leaning lbw for 17 but from that point bat dominated ball for the remainder of the day.
Bairstow looked in excellent form from the minute he came to the wicket and scored freely and a cut for four off Jack Shantry brought his 50 up off 48 balls with his 10th boundary.
Gale went to his half century off 106 deliveries with his sixth four off Saeed Ajmal who found little help in the pitch on the opening day.
Yorkshire scored 143 between lunch and tea and Bairstow raced to three figures with the aid of three fours in an over from Leach.
Gale flicked Ajmal to the fine leg boundary to reach the same milestone.
It was Brett D'Oliveira who broke the partnership as Bairstow, who had hit the previous ball for six, fell to a good tumbling catch by Tom Fell at backward point with the total 311-4.
Then Ajmal got in on the act as Adil Rashid (6) was pouched by Worcestershire skipper Daryl Mitchell who held onto a sharp chance at slip.
Charlie Morris took the second new ball and had Tim Bresnan on seven dropped at first slip by Whiteley with the total 341-5 in the 85th over.