That's all from the land of the egg-shaped balls for today.

We'll be back on Sunday, when it's Leicester's turn to go for the Champions Cup semi-finals. 

They host Stade Francais at 13:30 BST. See you then!

Saracens captain Brad Barritt has been speaking to BT Sport about a game of two very different halves for his side.

"A huge problem was our discipline in the first half. It was 9-1 in penalty count at half-time. Being on the back-foot played a big role," said the England back.

"But we're a team of guys who work hard for the team. Guys like Maro Itoje all stood up . We all stuck together and galvanized."

Paul Grayson
Former England fly-half on BBC Radio 5 live

"In the end you go back to the first half and the opportunity to put points on the board. Poor old Jamie Elliot made a mistake in not finishing off a try-scoring opportunity. Brad Barritt and Owen Farrell have been to the fore, Mario Itoje is just one of those players who always catches the eye."

It certainly wasn't vintage Saracens, but they've made it to the last four and maintain their unbeaten record in the competition. 

It's Wasps up next in another all Premiership tie. 

Image source, Getty Images

Billy Vunipola sweeps up from a Sarries scrum and they try to press forward towards the Saints 22.

Owen Farrell goes for a drop-goal, but it's weak and misses the posts. However, Sarries have already earned a penalty so they have another chance to extend their lead.

And Farrell nails it. Five minutes to go, and the hosts are pulling ahead.

JJ Hanrahan has come on for George Pisi as Northampton try to recover.

Ben Nutley is back on as well, after a head injury assessment.

Paul Grayson
Former England fly-half on BBC Radio 5 live

"Saracens are super dangerous in the second half. In the final 20 minutes fitness tells, strength in depth on the bench tells. A fantastic score from Chris Ashton, what we've seen over and over again from Saracens at their best, though they're not at their best today. Northampton will rue those missed opportunities in the first half."

Alex Goode floats a beautiful ball over the top to Chris Ashton, but the Sarries wing can't feed to Schalk Brits after Ken Pisi gets in the way.

The ball is kicked back into Sarries' half and they go on the march again, but play has been stopped as Ben Nutley is down injured. 

Nutley is forced off and Michael Paterson replaces him. 

Couple of replacements to report. 

South Africa great Victor Matfield is on for Christian Day for Saints, while Campese Ma'afu is on for Alex Waller.

Sarries earn a penalty and Owen Farrell quickly pings the ball forward into touch. They're going for the maximum.

Paul Grayson
Former England fly-half on BBC Radio 5 live

Image source, Getty Images

"This will go down to the wire."

Saracens smash Northampton in the scrum with a huge surge forward and they're going for the three-pointer.

Owen Farrell lines up his shot out on the left. Silence around Allianz Park, bar the whistle of the wind.

It's a one-point game again. 

Image source, Rex Features

Maro Itoje, who was so impressive for England during the Six Nations, intercepts a Saints line-out and it stalls play. 

And now Sarries are charging forward - Owen Farrell to Chris Ashton but arrrgh... Alex Goode can't get a handle on the pass. He looks very frustrated. 

Image source, Getty Images

Saracens flanker Will Fraser has been penalised for the umpteenth time. He's probably lucky to have avoided the sin-bin for multiple offences. 

He's failed to release the tackle this time and it's a penalty to Saints. Stephen Myler is going to have a go in the swirling wind... it's over.

Northampton extend their narrow advantage. 

Owen Farrell doesn't miss those ones. He slots with ease from close range, dead centre.

One point in it now.

Oh, and once again, Mako Vunipola has lost his contact lens. This happens in every game, I swear. 

A replacement for Sarries as well, as Jackson Wray makes way for Michael Rhodes. 

Image source, PA

Paul Grayson
Former England fly-half on BBC Radio 5 live

"We said before the game if this was going to be a contest Northampton would have to be at 100% and Saracens a bit below their best and that's the way it's been so far.

"Saracens lack accuracy in everything they do. There's been no flow or dynamism from their clearance work, it's been very un-Saracens-like." 

Billy Vunipola tries to sneak through at the back of the scrum but the Saracens number eight is pole-axed to the floor by Teimana Harrison. 

But now Sarries are gaining ground in attack. Brad Barritt powers forward, and they win a penalty bang in front of the posts. 

Image source, Getty Images

Image source, PA

Ben Foden is forced off through injury so young Harry Mallinder is on for Saints at full-back. 

He is, of course, son of director of rugby Jim and he's been impressive in his breakthrough season in the team.