A third century of the season by Surrey's enigmatic left-hander Usman Afzaal lit up a dull day at The Oval where the hosts recovered from a sticky start to post 334 for four against LV County Championship Division Two promotion hopefuls Glamorgan.

Afzaal sauntered in with his side in trouble at 51 for three to oversee their recovery with an excellent unbeaten 170 in dreary, overcast conditions where bad light might have played more of a part had Glamorgan skipper Jamie Dalrymple insisted on sticking by his pace bowlers.

Afzaal, whose season's best of 204 not out helped inspire Surrey's only championship win of the season against Northamptonshire, sparked the fightback by featuring in a fourth-wicket stand worth 103 in 30 overs with Arun Harinath (57).

Then, the 32-year-old combined with fellow left-hander Matt Spriegel (71no) to post a further 180 for the fifth wicket when bad light forced the eventual close at 5.20pm.

Surrey lost both openers inside 10 overs after winning the toss and electing to bat. Michael Brown (nine) chopped on when attempting a back-foot force against James Harris then Garnett Kruger had Jonathan Batty caught down the leg side by Mark Wallace following an airy waft off the hip.

Home captain Stewart Walters (seven) helped his side reach 50 but went soon afterwards, playing indecisively to a Kruger off-cutter to go lbw.

Harinath, a stylish left-hander who plays league cricket for nearby Sutton, combined forces with the equally elegant Afzaal either side of lunch in a stand that featured some graceful cover-driving.

So it came as a surprise when Harinath, in attempting to work to leg against Robert Croft, picked out James Allenby at leg slip to go soon after posting his maiden first-class 50 for Surrey.

Afzaal reached his first hundred at The Oval this season with a trademark cover drive that flew to the ropes at deep point with a modicum of effort yet with sublime timing. It was his 22nd boundary from his 173rd ball faced.

On a great day for the left-handers, the wiry Spriegel also reached a 50 from 87 balls and with seven fours. He might have gone for 45 when wicketkeeper Wallace, diving to his left in front of slip, downed a difficult chance off the bowling of Mark Cosgrove, but remained to reach a career-best when passing 61 just before the close.

Glamorgan, who came into the game placed fourth in Division Two, now face an uphill task in their bid to overhaul Essex and Northants in the race for promotion.