Ajmal Shahzad and Kyle Hogg saw Lancashire to a thrilling two-wicket win with four balls to spare against fellow Division One strugglers Durham.
With rain preventing any play until 2.55pm, Lancashire had 44 overs to score the 144 runs they needed when they resumed on 56-1.
A half-century by overseas star Ashwell Prince looked to have set the champions on course for a comfortable first win of the season, particularly when they were 156-4 in pursuit of only 200.
But when skipper Glen Chapple was eighth out they still needed 32 to win in 5.4 overs, and it needed Shahzad and Hogg to see them home in a pulsating finish at Chester-le-Street.
It was also an injustice for Graham Onions, who had career-best match figures of 11-95 but was let down at the end by Steve Harmison.
Having removed Paul Horton the previous evening, Onions' figures on the day were 16-4-26-5. But when Harmison was recalled with Lancashire needing 22 off three overs, his first over cost nine and he began the final over with an
unreachable no-ball which bounced high over the batsman's head. Two balls later Shahzad drove him to long-on for the winning four.
Durham learned after their two-wicket defeat that they would have four points deducted because of their slow over-rate, leaving them with minus one point from the match.
It means they are now 14 points adrift of Worcestershire at the foot of Division One and 25 behind Surrey, who are third from the bottom.
Champions Lancashire are closing in on their first four-day win of the season despite a brilliant century from Durham's Ben Stokes.
Stokes struck a fluent 121 to help build a lead of 200, but the visitors were on course to haul that in after reaching 56-1 by stumps.
Stokes's knock was his first century since he made 185 against the same opposition last year, before suffering a badly-dislocated finger later in the match. He played in only one more championship game thereafter.
After carrying his bat in the first innings, Paul Horton fell lbw to Graham Onions' first ball of Lancashire's chase, but Stephen Moore and Karl Brown played with surprising fluency for the remaining 15.5 overs.
Durham's lack of support for Onions was underlined when Steve Harmison came on first change and his first three balls cost 11 runs.
The former England quick did follow up with three maidens but he will need to take wickets on the final day if Durham are to haul themselves off the foot of the table.
Paul Horton became the first player to carry his bat for Lancashire in 20 years but there were just 45 minutes of play possible on day two against Durham at Chester-le-Street.
After rain had wiped out the morning session, Horton was unbeaten as Lancashire were all out for 170 - adding 29 runs to their overnight 141-8 - a first-innings lead of 68 runs.
Durham seamer Graham Onions (5-43) removed last man Simon Kerrigan to complete his second five-wicket haul of the season.
Horton equalled Cyril Washbrook's score of 49 not out in 1935 and since then no-one has carried his bat for Lancashire for a lower score.
Durham faced only three balls in their second innings without scoring before the rain returned.
A total of 18 wickets at Chester-le-Street as Durham hit back against Lancashire on the opening day of the County Championship match.
Durham were bundled out for 102 before Lancashire stumbled to the close on 141-8.
Visiting captain Glen Chapple won the toss and opted to field - kicking off a feast of wickets as he tempted Mark Stoneman (8) into a false shot.
A trio of victims for Kyle Hogg followed, and once Luke Procter had ended the brief resistance of Dale Benkenstein (10) and Paul Collingwood (25), the tail quickly collapsed to see Procter finish with 5-17.
Lancashire then fared little better as Durham quick Graham Onions stated his case for a Test recall by dismissing four of Lancashire's top five batsmen for single-figure scores.
But opener Paul Horton dug in to remain unbeaten on 31 from 103 balls, while Kyle Hogg provided sturdy support with 23 in an unbroken stand of 32 which ensured a first-innings lead.