Saracens marched to their third Premiership victory on the run with a narrow win over Northampton.

But once again the Vicarage Road club can thank new South African fly-half Luke Smith who kicked 20 points, taking his personal points tally for the season to 68 points.

Smith got Saracens off the mark in scintillating form with three penalties in just 16 minutes. Northampton however soon bounced back with captain Paul Grayson adding a penalty before England winger Ben Cohen went over to score.

Saints were rewarded after they camped on their opponents' goal-line and three scrums later, forward Andrew Blowers scooped up the ball from the base to pass wide to Cohen. Grayson converted, putting Northampton into the lead for the first time.

But again the tables turned and Saracens put their foot on the gas, scoring 13 points in four minutes.

Smith added a penalty before kicking a spectacular drop goal from 40 meters.

Irish winger Daragh O'Mahoney then scored his first converted try of the season after he made the most of a break by team-mate Kevin Sorrell.

Again Grayson and Smith exchanged penalties in the second half but it was the visitors who this time looked more likely to score.

Former England Under-21 captain Mark Tucker made a break up the left wing only for Saracens' Brett Sparg to bring the centre down at the last minute.

But Saints did not give up and instead continued to apply the pressure with John Phillips, Steve Thompson and Luca Martin all looking likely to score.

Finally hooker Thompson took Saracens by surprise deep into injury time and cut through under the posts to score. Full-back Grayson converted to make the final 25-20.

Teams:

Saracens: Harbut, Russell, Phillips, A. Benazzi, Roche, Hill, Roques, Cole, Walshe, Smith, O'Mahony, Sorrell, Horan, Sparg, Winnan.

Replacements: Cairns for Russell (73), Flatman for Phillips (52), K. Benazzi for A. Benazzi (71), Cheesebrough for Roche (56), Hampson for Walshe (65).

Not Used: Haughton, Arasa.

Sin Bin: Smith (77).

Tries: O'Mahony. Cons: Smith. Pens: Smith 5.

Drop Goals: Smith.

Northampton: Todd, Thompson, Budgen, Newman, Phillips, Rennick, Blowers, Seely, Malone, Hepher, Cohen, Tucker, Martin, Beal, Grayson.

Replacements: Dawson for Malone (60).

Not Used: Brotherstone, Morris, Hunter, Soden, Moir, Brooks.

Sin Bin: Todd (40).

Tries: Cohen, Thompson.

Cons: Grayson 2.

Pens: Grayson 2.

Att: 8,527

Ref: Rob Dickson (SRFU).