In what was a dramatic 90 minutes of football, John Sutton hit the net after only 5 minutes but a sensational free-kick from Charlie Adam was followed by a Thomas Buffel strike before the interval.
Sutton bagged his second from the penalty spot on 76 minutes but, just when it looked like the home side had earned a point, Novo smashed home the winner from close range to give his team three vital points.
Paul Le Guen made two changes from the squad that faced Livorno on Thursday night with Sasa Papac returning to the starting eleven in place of Karl Svensson and Dado Prso in for Novo.
The manager elected to stick with his attacking 4-3-3 formation with Prso, Boyd and Buffel doing most of their work in the last third of the pitch and Ferguson Hemdani and Adam just behind the forward trio.
His tactics did not, however, go according to plan in the early stages and after only five minutes Saints winger Simon Lappin found space on the left wing before swinging a perfect cross into the danger area. Striker John Sutton rose above Papac and Rodriguez to head beyond Letizi and give the home side a perfect start.
The home fans, as expected, were delirious with excitement at this stage and it could have got worse for Gers only two minutes later when Richard Brittain drilled in a low cross from the right but Sutton missed the ball from six yards before it was cleared to safety.
There was more concerns for Le Guen when Barry Ferguson looked to have picked up a stomach injury after a clash with Lappin but referee Calum Murray let play continue until Dado Prso was brought down by Millen 20 yards from Tony Bullock’s goal.
The free-kick was tailor made for Charlie Adam on his return to Love Street and the 20-year-old, who was on-loan at the Saints last season, gave Bullock no chance with a scorching strike which was equal, if not better, than his goal in Italy four days ago.
Having got themselves back into the game, Rangers started to dominate proceedings and only seven minutes later Buffel put his side in front but only after Julien Rodriguez had been booked for a rash tackle on Lappin.
Stevie Smith played a long ball up to Boyd and the striker, often criticised for his play outside the 18-yard box, cushioned the ball beautifully into the path of the Belgian who finished confidently with a low shot which crept inside Bullock’s right-hand post.
St. Mirren continued to show dogged determination despite being a goal down and Gus McPherson’s ploy to get the ball to Lappin and get crosses into the box caused the Gers backline problems in the opening period.
Rangers, however, held on to their slender advantage until half-time and they deserved to have their noses in front at the interval.
The tempo at the start of the second-half was somewhat slower with Rangers intent on keeping the ball and frustrating their opponents who were sitting 7th in the SPL before today’s fixture.
Charlie Adam was clearly enjoying his return to his old stomping ground and he tried his luck within ten minutes of the re-start but his 35 yard effort was high and wide of goal.
It had been a quiet afternoon for striker Kris Boyd and the Gers’ prolific hitman had to wait until 59 minutes for his first real attempt after Stevie Smith had been brought down 25 yards from goal after linking up well with Dado Prso.
Boydy’s low effort from the set piece looked to be going in after it had taken a deflection off a Saints defender but Bullock did well to stick out a leg and stop the ball from going in.
The Scotland star was starting to cause a few problems and the Rangers fans voiced their frusutration when David van Zanten climbed over Boyd in the 18-yard box when challenging for a high cross but the referee refused to point to the spot.
St. Mirren continued to push forward in search of an equaliser and whipping in crosses looked to be their most effective route to goal.
On 72 minutes Brittain again played a delightful ball into the area and Sutton’s excellent header, which was heading toward the top corner, was plucked from the air by Letizi.
Van Zanten was next up to deliver a cross on 76 minutes, again from the right, and this time Rangers were punished when Rodriguez was adjudged to have pushed substitute Corcoran and this time the referee blew for a penalty.
It looked a soft decision from the official but Sutton did not care and his rather tame spot-kick went under Letizi to level the scoring.
Le Guen elected to throw on Nacho Novo in place of Prso immediately after the goal and this proved to be an inspired move.
With only six minutes of the game remaining Adam found space on the left and when his low effort was saved by Bullock the Spaniard, who also found the net against Livorno, controlled the ball before gleefully netting the winner.
It was a remarkable end to an enthralling 90 minutes and Novo, with confidence now back on his side, came close to scoring a fourth late on when he volleyed over from 10 yards on the turn.
This might not have been Rangers prettiest win but, at the end of the day, three points is all that mattered and the relief on the Rangers players faces at the final whistle said it all after a tough battle in Paisley.
ST. MIRREN: Bullock; McGowan (Corcoran 69), Millen, Broadfoot; van Zanten, Murray (Kean 85), Brady, Brittain; Sutton, Mehmet (McKenna 69)
Subs Not Used: Smith, Reid, Molloy, McCay
Bookings: Brittain (30)
RANGERS: Letizi; Smith, Rodriguez, Papac, Hutton; Adam, Hemdani Ferguson, Prso (Novo 85); Buffel, Boyd (Sebo 87)
Subs Not Used: McGregor, Rae, Svensson, Ponroy, N’Diaye
Bookings: Rodriguez (20)
Referee: Calum Murray
Man of the Match: Charlie Adam