Despite a hat-trick by Darren Gough as Headingley enjoyed a first taste of day-night cricket, Lancashire won by 101 runs to go four points clear in the AXA League table as Yorkshire were dismissed for just 81 in 25 overs.
Lancashire, finalists in the NatWest Trophy and still in contention for the Championship, have two AXA League matches left but could be pipped to the title by Essex, who have a game in hand.
However, Essex have to go to Scarborough on Sunday and will find Yorkshire determined not to hand them easy points.
"We have to do better," Byas said. "We need points against Essex and in our other remaining games to keep our place in the top nine and so get into the First Division of the new league next season."
This is the last season of cricket's 40-over format, with the AXA League and Benson and Hedges Cup giving way to a two-division National League based on 50-overs matches.
Apart from their encounter with Yorkshire, Essex are due to meet Nottinghamshire at Chelmsford on 6 September before concluding their programme at Leicester on 13 September. Lancashire face Gloucestershire at Old Trafford on 7 September, two days after their NatWest final against Derbyshire, and finish with another floodlit fixture against Nottinghamshire at Trent Bridge on 9 September.
Gough's hat-trick thrilled a Headingley crowd of more than 10,000, and it could signal that day-night cricket is here to stay.
The Yorkshire marketing director, Mark Newton, said: "The response has been fantastic and commercially this is definitely the way forward for cricket in this country.
"We reckon that 50 per cent of the crowd was made up of non-members, compared with 15-20 per cent for a normal AXA League game. And quite a large proportion of those will have been tempted to watch cricket for the first time.
"I can see these games becoming a major part of the calendar, perhaps even with a shorter version of the game lasting just a couple of hours or so to appeal to younger people and introduce them to the game."
P W L D NR Tot
Lancashire (3) 15 10 2 0 3 46
Essex (7) 14 9 2 1 2 42
Warwicks (1) 15 7 5 0 3 34
Leics (4) 14 7 5 0 2 32
Middlesex (16) 14 7 5 0 2 32Reuse content