Nottinghamshire kept alive their hopes of qualifying for the semi-finals of the CB40 competition thanks to a rain-affected win over rivals Somerset.
Somerset hit 156-6 from 19.2 overs but Notts chased down a revised total of 143 in 16 overs to win.
Nottinghamshire coach Mick Newell told BBC Radio Nottingham: "I would say our chances are still less than 50-50.
"It is out of our hands but we have to make sure we beat Lancashire and that will give us a chance."
He added: "We are relying on other results and it could go down to run-rate.
"There's an outside chance we can still finish top and we could also finish as the best runner-up, so we have to beat Lancashire."
Only the top team in each of the three groups will progress, with the fourth spot going to the best runner-up.
And although Notts are now two points clear of Somerset in group C, they have played two games more.
Should Notts fail to win their group they have a decent chance of qualifying as the best-placed runner-up from the three groups.
Durham and Middlesex are currently their closest rivals but Notts still harbour realistic hopes of finishing top thanks to their win at Taunton.
Luke Fletcher took 3-27 to help restrict Somerset in the rain-hit match before further showers between the innings meant Notts were set 143 to win from 16 overs.
Rikki Wessels, Samit Patel and debutant Darren Bravo all fell cheaply, but Steven Mullaney hit 50 and skipper Chris Read struck a quickfire 42 as Notts reached their victory target with one ball to spare.
Newell added: "We knew the weather would be a factor so decided to bowl first when we would normally have batted.
"Mullaney has been batting at seven and hasn't had much of a chance but did very well and Chris Read has been consistently excellent for us."
Nottinghamshire, who lost three of their opening four games in the competition, play their final group game against Lancashire at Trent Bridge on 29 August.