Sale cemented their top-two spot in the Premiership with a hard-fought bonus point win at third-placed Harlequins.

Joe Marchant crossed to put the hosts three points behind before Akker van der Merwe finished off a driving maul.

Cobus Wiese powered over for Sale's fourth try and Nick David slid over late on for a Quins consolation try.

Second-placed Sale are now 12 points ahead of Harlequins, with a third straight league defeat leaving the south-west London club above Gloucester on points scored.

Meanwhile, Sharks flanker Tom Curry will have given new England head coach Steve Borthwick an injury scare ahead of the upcoming Six Nations when he limped off in the 16th minute after his right leg was trapped awkwardly during a tackle by Wilco Louw.

Wet weather at the Twickenham Stoop made playing conditions difficult but, after an early Allan penalty, Sale's backs spread the ball across the field and Luke James opened up space nicely for O'Flaherty to get the game's first try in the 18th minute.

Du Preez grabbed the second six minutes later when he touched down a low kick through by Sam James.

Quins got back in the game 67 seconds after the restart when the Sharks defence failed to deal with a high kick from Allan and Marchant gathered and scampered forward to dive over in the left-hand corner.

Allan failed to add the extras and Sale restored their eight-point lead 11 minutes later when Van Der Merwe dabbed down.

Italy international Allan was then stretchered off following a clash of heads with Manu Tuilagi before Sale's fourth score from Wiese came following more strong work by their forward pack.

David wriggled through to score to set up an interesting final five minutes but Will Edwards missed the resulting conversion, meaning Quins failed to pick up a losing bonus point.

With Sale now nine points behind runaway leaders Saracens, the congested nature of the Premiership table is underlined by Quins being just five points ahead of ninth-placed London Irish after the Exiles beat Bristol Bears.

Harlequins head coach Tabai Matson told BBC Radio London:

"This is another kick in the guts for us. We were in the fight with 15 minutes to go.

"Lots of things went much better than last week but, in conditions like this, we need to do a better job if we are going to create enough scoring opportunities to put Sale under more pressure.

"If you are not attacking well, you have to defend well. And we didn't do that well enough.

"I can't believe we have lost three in a row and we are still in third position. The next couple of games are critical and we have to get our Premiership season back on track."

Sale director or rugby Alex Sanderson told BBC Radio 5 live:

"We rocked up and it was really bad weather and the pitch was really muddy. I looked around and all I could see was smiles, maybe because it reminded us of home.

"The lads knew what they had to do, and we leant into a territory and kicking battle. We got most of the small things right.

"We feel like we are in a decent spot, and that showed the way we were able to wrestle back momentum and ascertain some dominance.

"We are not out of sight (in the table) by any stretch. It's a buffer, that's all it is."

On the injury to Tom Curry: "We are predicting a low grade hamstring injury.

"He will have a scan [on Monday]. These things don't turn around in a week, but I've already said to him 'you get your head on for the Six Nations now'."

Harlequins: David; Murley, Marchant, Esterhuizen, Bassett; Allan, Care; Baxter, Walker, Louw, Hammond, Herbst, White, Wallace, Dombrandt (capt).

Replacements: Musk, Els, Kerrod, Matthews, Lawday, Gjaltema, Edwards, Beard.

Sale: L James; Reed, S James, Tuilagi, O'Flaherty; R Du Preez, Warr; McIntyre, Van Der Merwe, Schonert, Wiese, Hill, T Curry, B Curry (capt), J-L Du Preez.

Replacements: Ashman, Rodd, Harper, Beaumont, Ross, Thomas, Curtis, Carpenter.

Referee: Wayne Barnes