A sensational left foot strike from Kris Boyd and a wonderful outside of the boot effort deep in extra time from Pedro Mendes won the match but my goodness it was a struggle.
Thistle deserved to take the match to added minutes such was their determination but fortunately for Rangers, Mendes was on the mark to send Rangers into the last eight.
Kris Boyd has made his name for typical striker’s goals but his strike at Firhill to give Rangers the lead was something very special.
He is synonymous with six-yard box finishing but his effort on 25 minutes was truly spectacular.
In fairness, he has scored some classics in his time but his left foot volley was breath-taking.
Steve Davis was the man who provided the ammunition with a diagonal ball from 30 yards out and Boyd met it so well giving Jonny Tuffey absolutely no chance.
Rangers deserved it for their dominance of the early proceedings. Pedro Mendes had been pulling the strings in midfield with some terrific passes and it was only a lack of finishing that let Rangers down,
The Portuguese playmaker brilliantly found Nacho Novo in five minutes and he forced a decent save out of Tuffey with a low drive to the left corner.
Then in seven minutes Boyd was played in by Davis but he miss-hit his shot perhaps thinking he was offside as appeared to be the case.
Jean-Claude Darcheville, given his first start of the season, should have done better in 12 minutes when he was set up by Thomson but instead of shooting he tried to play in Boyd and made a mess of the pass.
In fairness to Thistle, instead of buckling after losing the goal they rose to the challenge.
Neil Alexander had to pull off a very smart save to push Stephen McKeown’s snap shot over the bar in 27 minutes.
But he was helpless when the former Airdrie United man scored a terrific equaliser to stun Rangers six minutes later.
It was Simon Donnelly who set up the chance, playing in McKeown in the right channel and he drove a low shot into the left corner.
The Rangers bench, however, were not impressed and they were holding their heads again in 40 minutes when Novo blew a great chance to restore the lead.
Madjid Bougherra started the move with a great ball forward for Darcheville who did the right thing by laying the ball on a plate for the Spaniard but he got it all wrong by firing over the bar.
Novo tried to make amends four minutes later when he did well to cut in from the left and hammered a low shot which Tuffey pushed away with aplomb.
Rangers, who were quite comfortable early on, were in a cup tie alright as Thistle came at them in the early stages of the second half.
It took until the 64th minute before another decent chance came their way when Sasa Papac picked out Mendes 25 yards out but his shot sailed over the top.
Rangers kept pressing and Bougherra and Novo won corners with their perseverance but nothing was forthcoming.
But Thistle, who took Rangers to a replay in the quarter-finals of the Scottish Cup last season, stood firm and gave as good as they got.
Mendes’ influence dwindled as the game went on as it turned into a typical Scottish cup tie and the frustration among the fans was clear, although the fomer Portsmouth man was to have the final say.
DaMarcus Beasley was sent on for Darcheville in 73 minutes but he scarcely had a chance to influence things such was the frantic nature of the contest.
Rangers resorted to quick balls forward rather than more measured play and the Thistle defence eat it all up,
Indeed with three minutes of normal time remaining they came desperately close to winning it.
Former Aberdeen midfielder David Rowson suddenly found himself racing in on goal but Alexander was equal to the challenge, charging from his line to make a brave blocking save.
The danger was not over as the ball broke to Chris Turner – the Northern Irishman who had a trial with Rangers – but his follow up was equally well saved by Alexander.
Then in the final minute of normal time Novo had a better chance to settle things when Beasley played him in but he blasted over and extra time followed.
Rangers looked stronger in the opening moments with Beasley finally finding a bit of joy against full back Simon Storey.
Three times in the first period he got away from his man but on each occasion his cross did not find a blue jersey.
It really wasn’t Novo’s night. He was given another excellent chance in 99 minutes when Davis slid the ball through to the right side of the box and he drove a low shot wide.
Walter Smith took him off six minutes into the second period throwing Kyle Lafferty into the action as Rangers fought to win the match before the lottery of spot kicks.
He was given the left midfield slot with Beasley moved up to try to stretch Thistle and the tactic nearly paid off in 115 minutes,
The American star burst forward from just inside the Thistle half and played in Boyd but he blasted over the bar.
However, a minute later Mendes won it for the Ibrox men with a touch of sheer class,
Taking a pass from Beasley he used the outside of his right boot to swerve a fantastic shot past Tuffey and he raced to the Rangers fans behind the goal to celebrate the moment,
The yellow card which followed was incidental. The game was finally won.