Feroze Khushi scored a century on his List A debut for Essex in the Royal London Cup clash at Durham, but it proved in vain as they s suffered a two-wicket defeat.
Alex Lees scored a career-best knock of 126 to guide Durham to a nail-biting win via the DLS method at Emirates Riverside.
Lees anchored the Durham chase single-handed as no other player in the batting order passed 25, notching his second ton of the campaign.
The Yorkshireman held his poise on a slow wicket to notch his highest List A score, striking the winning runs off the first ball of the final over to lift the North-East outfit top of Group A with two matches remaining.
Khushi's century helped visitors post 227 for six in an innings that was interrupted by the rain. Although the Eagles mustered a competitive score from their 45 overs due to the elements, the hosts kept their composure to claim the win.
Rain delayed the start of the contest by 15 minutes before Durham inserted the visitors and Sir Alastair Cook began with a flourish drilling Jack Campbell for three early boundaries.
But, Chris Rushworth removed the former England skipper through a combined juggling effort from Scott Borthwick and David Bedingham in the slip cordon.
Nick Browne endured a struggle, scoring only three runs from 18 deliveries before edging behind to Cameron Bancroft. And captain Tom Westley continued the procession to the miserly Rushworth, picking out Liam Trevaskis at mid-wicket.
Khushi steadied the ship in a partnership with Josh Rymell before a heavy shower halted the action for 45 minutes. Despite the delay, Khushi regained his composure and reached his half-century, making the most of a second opportunity after being put down by Trevaskis on 14.
Khushi and Rymell manoeuvred Essex into a strong position to attack the closing overs with a partnership of 101. Campbell prised out Rymell for a career-best 40 to break the stand, but the arrival of Ryan ten Doeschate allowed the visitors to accelerate.
After scoring only two boundaries to reach his fifty, Khushi found his range to push towards his century. The 22-year-old ensured he had a one-day debut to remember by nurdling a single off his legs to post his maiden hundred from 101 deliveries. He fell in the over for 109 to Campbell, although he ensured that his side racked up a solid score.
Chasing a revised total of 232 due to DLS, Lees made a watchful start failing to score from his opening 10 balls before exploding into life with four consecutive boundaries.
The Durham openers passed fifty, but Aron Nijjar made the breakthrough as Graham Clark was caught on the fence by Khushi for 24.
Spin brought the visitors back into the game as Simon Harmer bowled Scott Borthwick with a yorking delivery before pinning Bancroft lbw.
Luc Benkenstein, son of former Durham skipper Dale, then claimed his maiden List A wicket by clean bowling David Bedingham for two.
Lees stemmed the tide by passing fifty for the second game in a row, and combined for a partnership of 51 for the fifth wicket with Sean Dickson. He fought a solitary battle against the visitors amid a clatter of wickets at the other end.
Lees was rewarded by scoring his fourth List A century from 113 balls, whittling down the total required in the process.
Luke Doneathy's run out and a wicket for Westley left Durham requiring three off the final over. Lees avoided further drama by dispatching the first ball to the leg-side boundary to secure the win.
Khushi said: "It was great to score my maiden List A hundred on debut. It was a great atmosphere here, but I'm disappointed that we failed to win the game because it would have made it all the sweeter.
"I've been batting well recently, and I backed myself to go out there and perform. It came off for me today.
"The rain delays did not help because it stopped our momentum. I was in the 40s and I wanted to carry on because I was in a good flow. We thought we had a defendable score, but Lees batted well to see them over the line"
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here