THE rigours of Rangers' season will crystalise in Florence this week when they play their 60th game, one that will determine whether or not they progress to a first European final in 36 years.

On Thursday night, Walter Smith will gaze around the dressing room of the Stadio Artemio Franchi looking for leaders. He will be thankful that, for all the men he's witnessed falling recently, the considerable presence of Carlos Cuellar remains.

The Spaniard has been absent just twice this season - against East Stirling in the Scottish Cup and, crucially, for the Old Firm defeat last Sunday.

Cuellar also missed the last 20 minutes of the first instalment of the Glasgow derby after deliberately handling Shunsuke Nakamura's goalbound shot and taking one for the team in the shape of a red card.

That had looked to be a worthwhile sacrifice until the late winner from Jan Vennegoor of Hesselink. But the full impact of Cuellar's absence was felt at the weekend, more so than in the first game.

Hindsight is a wonderful asset, but Smith could have been fairly sure Cuellar would have been able to deal with the long balls into the heart of the Rangers defence that contributed to the first and third Celtic goals.

His defensive rock was lost, Davie Weir went soon into the second period through injury.

The axis of Rangers' rearguard for most of the season has been the Allan McGregor, Weir and Carlos combination; without them, the defence looked extremely vulnerable.

As Smith watched the likes of Christian Dailly and Amdy Faye - remember him? - manfully battle to try and save the Old Firm match, there was certainly no criticism, or any feeling that the right kind of endeavour wasn't there.

But, in general, quality players decide games. And the absence of Cuellar in particular was telling.

"Carlos has been phenomenal for us this season and it was a big loss for us in the heart of the backline," Smith said.

"Davie Weir had to come off just a few minutes into the second half and at that stage, with Carlos not there, we had Christian, Amdy and a new goalkeeper in Neil Alexander in our back lot.

"So, clearly that kind of disruption has been a factor for us, given that our defence had been one of the most consistent parts of our team up until the past couple of weeks, when players dropped out through injury and suspension.

"We did give Celtic the goals very easily and it was poor defending from our point of view."

Smith is well aware that major questions will now be asked of his squad. Although Motherwell have their own ambitions to pursue at Fir Park this Saturday lunchtime, Celtic will be favourites to open an eight-point gap ahead of what is always a treacherous trip for Rangers, to face Hibs on Sunday.

Rangers will either be in the Uefa Cup Final by then or dealing with the crushing blow of falling at the semis. Either way, Hibs is a must-win.

"We will be able to clear the decks a little after Thursday and see exactly what we have in front of us in terms of the fixtures. We'll go from there in terms of the SPL challenge," Smith continued.

"We just need to keep our focus, starting at Easter Road, which is obviously a tough venue at any time for Rangers, never mind coming off the back of a European match and with a lot of players out.

"If we win our games in hand we'd be four points clear. If we keep playing like we did at Parkhead, and put in that kind of effort, I'll be happy, and hopefully we will get the rewards.

"If you look at the Old Firm games, both sides have taken six points each at home. So it will come down to what we both do against the other teams and, as I have said all along, there are no easy matches.

"Of course, we would have liked to have taken something from the back-to-back games at Celtic Park, but we haven't and we just need to try and win our matches. We are still in there fighting."

Smith conceded in the aftermath of Sunday's defeat that his target was always to close the gap and challenge Celtic this season. That Rangers have done, and the fact they have continued to storm along in three other cup competitions is admirable.

Such is the nature of life in Glasgow, however, the manager and players will still come in for stick if they don't deliver the title in the run-in.

To that end, a return from the back-to-back visits to the East End would have allowed slightly more breathing space, but Smith is well aware his men just have to concentrate and try to secure the five wins they need from the six remaining matches.

He added: "I said after we lost the first game at Parkhead a couple of weeks ago that people had got their assessment of the league championship wrong. There were far too many people happy to jump to conclusions when we knew how difficult it would be going to Parkhead twice in a row and with Celtic's home record.

"You also had a situation where, due to our cup matches, Celtic were playing their SPL games and that has given them an opportunity to collect points.

"Overall, I think it was a bit unfair we lost both games. Okay, in the first match I didn't think we deserved to win looking at the general play.

"But we lost a stoppage time goal which was extremely disappointing after battling for the last 20 minutes or so with 10 men.

"On Sunday, we played well and controlled the first half and I felt we should have had a point at least from that one."