Simon Zebo raced over for a hat-trick of tries to provide the perfect ending to a week in which he was invited to train with the Irish Six Nations squad, and Ronan O'Gara kicked 24 points as the two-times champions saved their best for last.

Having clinched the pool the previous weekend, this game at stadium:mk was all about securing a home draw. They did that and more as they overtook reigning champions Leinster to take the top seed position.

Northampton Saints knew they had to win with a bonus point to stand any chance of reaching the Heineken Cup quarter-finals and also had to be aware that if the Scarlets won in Castres, they could pinch a potential Amlin Challenge Cup place.

As for Munster, the only unbeaten team in the tournament after five rounds of pool matches, they needed to grab at least a losing bonus point to ensure they played their quarter-final at their beloved Thomond Park.

So there was all to play for, although Saints went into the game without their England trio of Chris Ashton (not selected), Tom Wood and Courtney Lawes (injured).

The home side came into the game on the back of five successive wins in all competitions and were seeking revenge for having victory snatched from their grasp by an 84th-minute Ronan O'Gara drop goal on matchday one.

They started well and Ryan Lamb rewarded their dominance with two early penalties.

O'Gara was quick to respond, but a penalty try awarded when the Munster pack disintegrated at a scrum in the shadow of their posts allowed Saints to move into a 10-point lead.

Munster looked slightly stunned, but their wealth of experience came to the fore and the metronomic boot of O'Gara gave them some impetus.

Munster had confirmed themselves as pool winners the previous weekend, but there was the tantalising prize of a record unbeaten march through their pool for the first time in their 17 years in the tournament if they could keep their winning run going.

Things were looking good when BJ Botha burrowed his way over from close range for a try and O'Gara's conversion was followed by a penalty that gave them the lead for the first time in the 37th minute.

But Lamb had the last laugh in the first half with another penalty and it was all square at the break.

The capacity 22,000 crowd were gripped by the action and there was no let up in the intensity when the action resumed.

With their home draw under threat, Munster flexed their muscles and two tries in a breathtaking burst seemed to have put the result beyond doubt. Johne Murphy rounded off some great play in the right corner and then Denis Hurley sent Zebo racing clear a few minutes later.

The 12-point lead was cut by a second penalty try awarded for another total destruction of the Munster scrum from five metres out, but the home side could not cut the gap to anything less than four points.

At 26-31 it was still anyone's game but even though Lamb matched two more O'Gara penalties, Zebo's interception try from 60 metres not only sealed the victory but guaranteed a home draw and took Munster ahead of the reigning champions Leinster to the top qualifying spot.

It was the first time this season in Europe that Munster had picked up a bonus point and now they have to break the Heineken Cup hoodoo by becoming the only team to win the trophy by winning nine straight games.

Zebo's hat-trick try and Ian Keatley's conversion took the score over 50 points and Scott Armstrong's last-minute try was hardly any consolation for the shattered Saints.