Middlesex proved to be this week's only three-day winners in the Bob Willis Trophy as they beat Sussex with just minutes to spare before the rain came down at Radlett.

Bob Willis Trophy: Middlesex beat the rain at Radlett to win, but luckless Somerset are denied victory by bad light

But just how crucial that may be now depends on just how accurate weather forecasts for Tuesday prove for the final day of this new red-ball competition's fourth round of games.

If, as is feared, the final day proves to be a total wash-out all round the country, then that would really concertina things in the battle to decide which two of the best group sides line up in the final at Lord's in late September.

And, after last week's weather frustration at Edgbaston, that could all leave poor Somerset as chief sufferers again.

A week ago, they were denied by the rain with Warwickshire's ninth-wicket pair at the crease - and the Bears' last man Matt Lamb nursing a broken toe and struggling to bat.

This week, they again have the opposition eight down, but may now have to spend the whole of Tuesday watching the rain come down at Taunton.

After having Gloucestershire 14-3 in a mess overnight, they had to wait until gone four o'clock before finally getting on the pitch, only to suffer a further weather break.

But, when they got a second window of 7.1 overs with four wickets needed very late on in the day, they claimed two of those scalps, only for the umpires to intervene for bad light. And the efforts of Craig Overton and Josh Davey, who both had figures of 4-25, may yet be all in vain.

North Group leaders Derbyshire had a useful third day of their game with Durham at Chester-le-Street.

Thanks to a century from Luis Reece (122) and half-centuries for Billy Godleman and Wayne Madsen, they lead Durham by 18 runs with six wickets remaining.

But the six bonus points they have picked up will increase their advantage over second-placed Yorkshire if the heavens do indeed open as forecast.

They would have 14 from the game, as opposed to the Tykes' haul of 11 if no further play is possible in County Durham or in Leeds and both games end in a draw,

In the Roses Match, Lancashire openers Alex Davies and Keaton Jennings shared their second successive century partnership as they replied with 195-5 to the 260 made by Yorkshire, for whom Adam Lyth hit his fourth century in this fixture.

In the North Group's other game Leicestershire skipper Colin Ackermann made an unbeaten 58 to halt Nottinghamshire's push for victory.

The Foxes closed with only a 22-run lead on 143-3 - but, like everywhere, that may all prove meaningless in the morning.

This week's fourth round of fixtures began with still six of the 18 counties still winless. That was always likely to change at Wantage Road where the Central Group's bottom two Northamptonshire and Glamorgan were playing each other.

It looked like Northants were nailed on to break their duck when they reduced Glamorgan to 28-6 in their second innings, still 45 runs behind. But the visitors' tail rallied, inspired by Dan Douthwaite.

He made 86, putting on as astonishing 168 for the ninth wicket with big-hitting South African Marchant De Lange, who rode his luck to hit nine sixes and six fours in his maiden century - 113 off 78 balls.

The second century of the game by a Glamorgan tail ender, after Callum Taylor's first-innings ton, helped Glamorgan to 259 all out, but Northants had knocked off 62 off them for the loss of just one wicket and need only another 127 to win.

While luckless Somerset wait to see what the weather gods have in store at Taunton in the West Country derby against Gloucestershire, the Pears-Bears Midlands derby seems destined for a draw.

Former skipper Daryl Mitchell made his 38th first-class century as Worcestershire reached 410-7 to earn a first-innings lead of 55, but Warwickshire skipper Will Rhodes then added to his first-innings 207 with a further 42 before the close to wrest back the lead.

The late Middlesex victory over Sussex has made the South Group suddenly very interesting.

England hopeful Ollie Robinson, fired up after an official umpire's warning for dissent, took 3-3 in nine balls in a haul of 4-54 but Middlesex kept their heads and won the rain chase on 193-5 to win by five wickets, John Simpson and Martin Andersson sharing a crucial stand of 63 to complete their second Trophy win.

It moves them to 59 points, which would be within 11 of leaders Essex, who had won their first three games but may only pick up nine points from the game if they do not get on the pitch again at Arundel.

Sir Alastair Cook made yet another century - his 66th in first-class cricket - but not even his status in English cricket looks like saving the Essex-Hampshire game ending in a draw.

After no play on the first day and only 47 overs on day two, Arundel was already the hardest hit of this week's nine grounds even before only 31 were possible on the third day.

Cook was on 129 not out looking well set for a big one, when Essex lunched on 249-3 in their first innings. But torrential rain ended play for the day - and the forecast is even worse for Tuesday's final day.

In the other South Group game, Rikki Clarke took three wickets for bottom club Surrey for just one run in his first three overs against Kent.

He ended up with 5-15 to leave Kent on 118-9, leading by only 182 overnight, if the final day goes ahead.