Tom Fell scored a career best 143 to help earn Worcestershire a first innings lead of 76 on the third day of the LV = County Championship match with Middlesex at Uxbridge.
Then the visitors picked up three wickets before Middlesex wiped out their deficit to keep alive their victory hopes.
Middlesex eventually closed on 140-3 from 48 overs – a lead of 64 with Paul Stirling unbeaten on 39 and Joe Burns 29 not out.
Fell completed the fourth Championship century of his career with his 16th boundary – off Toby Roland-Jones – from 174 balls out of 249-5 in the 86th over.
It was the second ton of the season for Fell after his 114 in the opening game of the campaign against Yorkshire at New Road.
His other hundreds were in back to back innings last season – 124 against Leicestershire at Grace Road and 133 off the Glamorgan attack at New Road.
Fell was eventually eighth out at 332 having batted for 311 minutes. He faced 228 balls and hit 22 fours and one six.
Some big hitting from Jack Shantry enabled Worcestershire to claim four batting points before they were bowled out for 385 in the 117th over.
Worcestershire resumed on 195-3 and lost the wickets of Alex Gidman, Joe Clarke and Ben Cox during the morning session in scoring 102 runs and reaching 297-6 by lunch.
Tim Murtagh made the first breakthrough in the second over of the day with Gidman, who had not added to his overnight 30, not playing a shot and being bowled.
Clarke looked in good touch and a two off James Harris brought up the 200 and the first batting point in the 76th over.
He then collected successive boundaries off Middlesex skipper James Franklin via a cover drive and then whipping him through the leg side.
But the first over with the new ball at 224-4 from 80 overs led to the undoing of Clarke (17) who was trapped lbw by Murtagh.
Fell slashed Murtagh over gulley for four to move into the 90s and cut Roland-Jones to the boundary before reaching three figures.
The 250 came up in the 88th over but then Ben Cox (6), having blunted the new ball for 11 overs, fell victim to a sharp catch by Ollie Rayner at second slip off Harris.
Fell was joined by Leach and the pair played positively either side of the lunch interval in adding 50 in 11.5 overs before Leach (19) went for a big drive and was bowled by James Harris.
Fell smashed Roland-Jones for six and two balls later his superb innings ended when, attempting another big hit off the same bowler, he was caught on the deep mid wicket boundary, being eighth out at 332.
Shantry then hit Roland-Jones for successive sixes and a two off spinner Ollie Rayner in the 110th over secured the fourth batting point.
The left armer was given good support by Saeed Ajmal in a ninth wicket stand of 53 in 10 overs.
Murtagh ended the innings by bowling Ajmal (20) and Charlie Morris (0) in the space of three balls to leave Shantry unbeaten on 41 from 48 balls with three sixes and two fours.
Murtagh finished with figures of 4-76.
Opener Sam Robson had fallen to Charlie Morris's first ball in the Middlesex first innings – and only survived one more at the second attempt.
He was drawn forward and nicked through to Cox who took a fine catch.
Nick Gubbins and Nick Compton added 49 by tea but both fell in quick succession.
Ajmal claimed his first Championship wicket since returning to New Road when he bowled Gubbins for 23.
Shantry then picked up the key wicket of Compton, who having made 47, edged through to Gidman at first slip at 73-3.
But Burns and Stirling were relatively untroubled in posting an unbroken stand of 67.
