Chris Jones
BBC Radio 5 live commentator

"That is a very, very tight call indeed and Saracens don't like it. It keeps Harlequins alive in this game because the kick would have been right in front of the posts."

Now Marcelo Bosch is through following a charge down, and it's another Saracens score. Hold on though, was he in an offside position when he picked the ball up? We're going to the TMO, and yes he was, it won't count! Let off for Quins.

Brian Moore
Former Harlequins and England hooker on BBC Radio 5 live

"Throughout this game, there have been various forms of idiocy. That was another one. There was no need for him to do that.

"Saracens will be confident of holding out from here."

Saracens' tails are up now. The ball is smashed high and long and Owen Farrell gives chase, only for Luke Wallace to pretty cynically step across the fly-half and the referee decides that'll be a penalty. Much, much better. It's over and the gap is now four. This is looking a bit ominous for Harlequins.

Saracens have a line-out in the corner and they work it well. They go inside now, and the ball reaches Brad Barritt. He's five metres out with plenty of bodies between him and the line, but does brilliantly to muscle his way through under pressure and touch down. Owen Farrell's conversion is good, and Sarries are in front once more.

That's a better set-piece from Quins. Nick Evans pokes the ball through but it goes straight out of play. Then, as Sarries try a quick throw, they lose the ball and it finds it's way back to Danny Care, whose audacious drop-goal attempt clatters back off the post. As ever, brilliant improvisation from the Harlequins scrum-half.

Chris Jones
BBC Radio 5 live commentator

"Harlequins will feel that, if they can score next, they'll have a real opportunity to reach Twickenham. It's been an inspired performance from them."

That's a big old scrum from Saracens, and I think it's Nick Easter who, in the end, concedes the penalty. This could be another long-ranger for Marcelo Bosch, but he's put it wide too! These misses are really totting up for Sarries, who are letting the visitors off the hook a bit.

That looks a sore one for Harlequins and England prop Joe Marler. He's taken a knock to the head, so the strapping is on.

London Welsh centre Seb Jewell summarising on BBC London 94.9: "That was a very rare miss. Kickers are very important in the modern game and Quins can count themselves very lucky to have got away with that indiscipline."

The home side are immediately on the attack and, as their maul charges for the line in the right-hand corner, referee Wayne Barnes decides that a Quins player entered from the side and Saracens will have a penalty. It all breaks down, so Owen Farrell will kick for goal... But that's wide again! Three misses from five attempts. May want to tweak that radar, Owen?

Saracens may have finished a whopping 20 points ahead of Harlequins in the final Premiership standings, but that'll count for nothing much in this remaining 40 minutes. Owen Farrell gets us back underway.

BBC Sport's Chris Osborne at Allianz Park: "Some heated conversations between both sets of players as they file into the tunnel below us. There is a feeling that Sarries were a little bit naughty on the charge down during Evans' conversion before the whistle."

You do wonder if memories of that semi-final loss to Saints are coming flooding back for Sarries fans. That was their first-ever defeat at Allianz Park, the ground to which they moved in February 2013. They've only lost one more home game since then - a Premiership defeat by London Irish in February - and they'll be desperate to prevent loss number three today.

And there goes the half-time whistle. What a seesawing, frantic end to the first half that was. Saracens, beaten by Northampton in their home Premiership semi-final 12 months ago, are 40 minutes away suffering the same fate again, this time at the hands of Harlequins.

Boy, has this semi-final burst into life. Poor hands from the hosts on half-way and Chris Robshaw manages to get a foot on the ball to hack it forward. The chase is on - and there's only one winner, Mike Brown! The England full-back charges through to touch down and Harlequins are in front again. Nick Evans kicks the extras.

Now, Marcelo Bosch is back on the field and immediately has a kicking opportunity after a Harlequins infringement at the breakdown in Saracens' half. But this is too far out, even for Bosch. Missed.

Brian Moore
Former Harlequins and England hooker on BBC Radio 5 live

"Remarkable from Saracens; a man down but still showing the ambition to get a try. That's very persistent, resourceful rugby.

"It just shows that, having got into the lead, Quins were not playing with their heads."

What a response! They may be two men short, but they're ahead again on the scoreboard. Straight from the restart Saracens have the ball back, but when they work it to Chris Ashton on the right Quins have plenty of cover to force him inside. But now they'll have a crack down the left-hand side, and here comes the big Scotsman Kelly Brown, and he's over! Terrific finish. Owen Farrell misses the conversion, but what a blow to Harlequins that is.

BBC Sport's Chris Osborne at Allianz Park: "Quins fans mocking the piped in 'stand up for the Saracens' music that gets played here with a very good, acapella version of their own."