Glamorgan paceman David Harrison took his first five-wicket haul for four years in seamer-friendly conditions at Lord's to leave Middlesex struggling to avoid their second successive defeat.

On a day which saw 17 wickets fall, the 28-year-old extracted movement through the air and off the pitch to bag five for 62 and dismiss the hosts inside 52 overs for a paltry 160 as they responded to Glamorgan's 315 all out.

They were Harrison's best four-day figures since his five for 76 against Worcestershire at New Road in May 2006.

After performances of early promise for England Under-19s, Harrison's career has since been blighted by back injuries, which wiped out his entire 2007 campaign.

Out of contract at the end of this summer, he is effectively bowling for his future with the Welsh county and, thus far, making a good impression.

In tandem with medium-pacer Jim Allenby, who swung the ball prodigiously under early-morning cloud cover to claim four for 29, Harrison proved nigh on unplayable for a Middlesex top order low on confidence and match practice, having lost all their pre-season friendlies to inclement weather.

England captain Andrew Strauss, with a patchy 44 from 68 balls, top-scored for the hosts before falling victim to Allenby.

Attempting a back-foot force through the covers, Strauss contrived to edge the ball onto off stump to go after 101 minutes at the crease.

Fellow left-hander Dawid Malan (17) went in similar fashion, misjudging an in-swinger that plucked out leg stump as Middlesex conspired to lose their last eight wickets for only 89 despite improving conditions and late afternoon sunshine.

Their worst culprit, John Simpson, looked comfortable in reaching 32 only to toss away his wicket lbw after missing a pre-meditated sweep against left-arm spinner Dean Cosker.

Though Glamorgan captain Jamie Dalrymple secured a first-innings lead of 155 he decided against enforcing the follow-on, opting instead to bat again and give opening bowler James Harris time to receive treatment for a leg injury that restricted his input to only seven overs.

Without the option of using the heavy roller to deaden the pitch, Glamorgan also found batting difficult second time around as they limped to 119 for six to extend their lead in the match to 274 going into day three.

They lost opening bat Mark Cosgrove retired hurt with suspected concussion for 17 after he ducked into a Steven Finn bouncer to be hit on the back of his helmet - six of his team-mates soon followed him back to the Lord's pavilion.

Having been dropped at long leg when on four, left-hander Gareth Rees (20) fenced a Gareth Berg lifter to second slip and Dalrymple went in similar fashion when edging an airy drive to the same fielder.

Ben Wright (four) played across one to go leg before and give Kiwi Iain O' Brien a much-deserved scalp, then Allenby (15) blotted his copybook by going lbw to Finn after being caught on the crease by a full-length delivery.

Michael Powell (47) missed out on a second half-century in the match when his back-foot waft cannoned onto the stumps via a bottom edge then, in the penultimate over of the day, Tim Murtagh bagged a second wicket by trapping James Harris (two) lbw.