READING FC could be counting the cost after Philip Billing nudged Jaap Stam's side further away from the Championship's top-two.

Royals were on course for a precious point at the home of their promotion rivals when the Dane crashed home an 82nd minute winner at the John Smith's Stadium to end their six-match unbeaten run.

Both sides have been nibbling at each other's heels for a number of weeks.

And there was little to choose between them again, with Reading's Roy Beerens hitting the post and Ali Al-Habsi saving a penalty from Terriers' Rajiv van La Parra.

But in the battle for third-spot, it was David Wagner's men who took control as they went four points clear of Reading with a game in hand after an 11th victory in 13 league games.

It means Royals' automatic promotion hopes could hinge on Saturday's clash at second-placed Brighton, eight points ahead having played a game fewer.

Suddenly, victory at the Amex could be a necessity if Stam wants to avoid the lottery of the play-offs - a format Royals rarely do well in.

Stam's men will also have to turn encouraging displays like this against their promotion rivals into big wins.

Leaders Newcastle United, fifth-placed Leeds and Sheffield Wednesday all lie ahead in the next six games - make-or-break time if ever it was.

Stam kept faith with the same 11 players who started in the 3-2 victory against Brentford a week earlier, with fit-again skipper Paul McShane making a welcome return to the bench.

But Royals got off to a sluggish start and struggled to keep pace with the lively Terriers.

Wagner's side enjoyed most of the early possession and went close on two occasions when a 25-yard van La Parra rocket flew narrowly wide before Elias Kachunga missed the target from a tight angle.

But Royals were an inch away from taking the lead with 34 minutes gone when Beerens cut in from the left, turned Billing inside out and arrowed a shot that looked destined for the top corner, only for Danny Ward to tip it onto the crossbar.

They also went close from the corner that followed, Liam Moore heading straight into Ward's arms from Jordan Obita's delivery when anywhere else would have done.

But Royals appeared to shoot themselves in the foot three minutes later when Tyler Blackett tripped Isaiah Brown in the box.

But Wagner's men were singing from different hymn sheets and, after Brown reluctantly handed the ball to van La Parra, the Huddersfield midfielder's spot-kick was brilliantly saved by Al-Habsi.

It was Brown's last action of the match and he was immediately hooked by Wagner, with Jack Payne sent on in his place.

The change appeared to briefly take the wind out of Huddersfield's sails, and Reading looked to capitalise after the restart.

They almost managed it in the 47th minute when Danny Williams played a neat one-two with Lewis Grabban before drilling an effort into Ward's arms from the centre of the box.

Former Royals target Nahki Wells replied four minutes with a shot that flew wide of the post.

But the visitors felt they were denied a penalty of their own moment later when Grabban went down under a Ward challenge, but referee Tony Harrington did not want to know.

As the tension grew, Blackett's clearance fell kindly for Kachunga who could only volley wide and, as the conditions got worse, both managers turned to their bench for inspiration.

Stam had used all three substitutions with 19 minutes to go, Adrian Popa, Yann Kermorgant and John Swift coming on for McCleary, Grabban and Jordon Mutch.

So when Huddersfield took the lead in the 82nd minute the omens looked ominous for Stam's men.

Al-Habsi looked to have saved his side by blocking from Payne as Reading defended a cross, but Billing kept his composure to steer home from eight yards.

It was a crushing blow for Royals and although Kermorgant looped a free-kick onto the roof of the net in the dying stages when Moore impressed as a makeshift striker, it was Wagner's men who claimed the victory.

Time will tell how damaging this loss will be in the race for promotion. But defeat in West Yorkshire will do little to raise hopes of winning at Brighton on Saturday (5.30pm ko).

Huddersfield: Ward, Smith, Hefele, Schindler, Löwe, Billing, Mooy, Kachunga, Brown, van La Parra (Lolley 66), Wells (Quaner 88). Subs not used: Whitehead, Hudson, Cranie, Payne, Coddington.

Reading:  Al-Habsi, Gunter (c), Obita, Moore, Blackett, Williams, Kelly, Mutch (Swift 71), Beerens, McCleary (Popa 61), Grabban (Kermorgant 71). Subs not used: Jaakkola, McShane, Evans, Meite. Booked: Kermorgant 90.

Referee: Tony Harrington.

Attendance: 19,894.