Rory Hutchinson's last-minute try helped Northampton win a thriller at Exeter to go top of the Premiership.

Ollie Sleightholme scored a hat-trick for the visitors, but his efforts looked in vain when Rus Tuima went over with eight minutes to go.

But Saints won a late line-out and a few phases later Hutchinson went over.

The win moves Northampton three points above Harlequins, who beat Newcastle on Friday, while Exeter stay third despite earning two bonus points.

The thought of Saints winning the game had seemed a far-fetched dream after the hosts made a superb start to the game.

Jacques Vermeulen went over at the start and end of a four-try spell in the opening 25 minutes, which could have seen Exeter score more but for some dogged defending on their own line by Saints.

The in-form Emmanuel Feyi-Waboso scored the pick of Exeter's early tries as he flew into the right corner after Henry Slade won a turnover and Harvey Skinner sent a great bouncing pass to the winger - who is on the radar of both England and Wales.

Saints finally got into Exeter's 22 for the first time after 25 minutes, and five minutes later they were over, having seen Dafydd Jenkins sin-binned for a head-to-head hit with George Furbank.

With the extra man scrum-half Calum Braley snuck in from close range and, two minutes later, they got a second as Furbank's excellent crossfield kick set Tom Litchfield away on a three-on-one break down the left wing and he fed Sleightholme, who coasted in under the posts.

Exeter saw Slade sin-binned six minutes into the second period after replays showed he elbowed Northampton's Burger Odendaal in the head, giving further confidence to their opponents.

Saints seized the momentum as Furbank went in against 14 men, and a minute after it returning to 15-a-side Alex Mitchell's superb dummy saw him break from halfway before sending Sleightholme over for his second to put Saints two points up.

Slade kicked a penalty to put Exeter a point in front after Ross Vintcent had had a try disallowed for the hosts, but soon after Furbank and Mitchell combined to set up Sleightholme's third to put Phil Dowson's side 35-29 up with 15 minutes left.

But the game took a further twist when Tuima broke through to score what appeared to be an Exeter winner, only for Saints themselves to go on and win it.

It the final minute they won a line-out deep in Exeter territory and, a few phases later, were camped on the Chiefs line, and with the hosts' defence narrow Mitchell flung the ball out to the unmarked Hutchinson who dotted down to win a thriller.

Exeter director of rugby Rob Baxter told BBC Sport:

"I've just said to the lads that I couldn't be any prouder of them than I am now.

"If Northampton mess up that last line-out or we scramble it into touch why would this feel any different to how it did in Toulon, when we kicked the last kick of the game?

"What you've performed in the game is still exactly how you performed in the game, but if the last score goes to the opposition in a way that it did today you've still got to accept everything that happened, over the 80 minutes.

"Over the 80 minutes did we get everything right? Of course we didn't. Over the 80 minutes did we do some good things? Yes we did.

"We've got to look at those things just as they are and take them for what they are."

Northampton director of rugby Phil Dowson told BBC Sport:

"We spoke during the week about how good they are straight out of the blocks, particularly at home - they've scored more tries in the first 10 minutes than anybody else.

"We talked about starting fast, we didn't, 26-0 down was about as poor as we've been, but I think those two tries before half time really gave us at least equilibrium to regroup at half time and get to a point where we could get back into the game.

"If it's 26-0 at half-time you're talking about a mountain to climb, whereas if you're talking 26-14 at least then you're saying 'we have hurt them, there is opportunity out there' and you can create some belief about it."

Exeter: Wyatt; Feyi-Waboso, Slade, Hawkins, Hammersley; Skinner, Townsend; Abuladze, Yeandle, Iosefa-Scott, Pearson, Jenkins (capt), Roots, Vermeulen, Fisilau

Replacements: Norey, Hepburn, Painter, Tuima, Vintcent, Cairns, Devoto, Wimbush

Sin-bin: Jenkins (29), Slade (46)

Northampton: Furbank (capt); Sleightholme, Odendaal, Hutchinson, Litchfield; F Smith, Braley; Haffar, Matavesi, Davison, Moon, Munga, Coles, Scott-Young, Graham.

Replacements: Langdon, Iyogun, Scott-Mills, Manayavanua, Pearson, Mitchell, Dingwall, Freeman.

Referee: Anthony Woodthorpe