Worcestershire rapidly made up for lost time after putting Middlesex into bat on the truncated first day of the LV = County Championship match at New Road.
Play did not get underway until 1.40pm after overnight and morning rain – but the home side bowled out their second placed opponents for just 98.
West Indies paceman Shannon Gabriel bowled with pace and hostility to finish with 5-31 on his home debut for the County.
But he received excellent support from Joe Leach and Jack Shantry with two wickets apiece.
And Worcestershire were razor sharp in the field, holding all their catches – including four by keeper Ben Cox.
Then Brett D'Oliveira and Tom Fell figured in an unbroken stand of 66 to steer Worcestershire to 79-1 by the close.
Six batsmen failed to trouble the scorers with only John Simpson (27 not out) and Nick Compton (19) offering prolonged resistance.
Leach took the new ball and struck in his second over as Paul Stirling (4) stopped on his shot and was caught by Brett D'Oliveira at cover.
Gabriel operated from the Diglis End and worked up a fair head of pace before taking two wickets in two balls.
First Angus Robson (17) edged the West Indian paceman and Tom Fell held onto a sharp chance at third slip.
Then the next delivery defeated Dawid Malan (0) for pace and knocked out his middle stump.
Neil Dexter played and missed the hat-trick ball from Gabriel and survived – but not for long.
Shantry came into the attack for Gabriel (5-2-10-2) and in his first over Dexter (0) pushed forward and was safely pouched at second slip by skipper Daryl Mitchell.
Shantry enjoyed another success as Middlesex skipper James Franklin (0) nicked a delivery which saw keeper Ben Cox cling onto a fine catch away to his left.
Leach removed former Worcestershire loan player Compton with Cox taking another good catch.
Middlesex were 64-6 at tea and Gabriel returned to the attack to trap Ollie Rayner lbw for 11 with the third ball after the resumption.
Cox then went across the slips to pull off another fine catch after James Harris (0) edged Gabriel.
Gabriel completed his five wicket haul when Toby Roland-Jones (0) attempted to hook a bouncer and Leach held the catch at long leg.
The innings was wrapped up by Barnard as Tim Murtagh (0) flashed outside the off stump and was caught behind to give Cox his fourth catch.
Mitchell (0) edged Toby Roland-Jones to second slip but then Brett D'Oliveira and Tom Fell responded with a half century stand.
By the close D'Oliveira had moved onto 38 from 81 balls with six fours and Fell 37 from 71 balls with seven boundaries.