There was a time when Liverpool's backline was the side's only real quality. As well as Steven Gerrard, of course.
Rafa Benitez endured many a taunt in the press about his apparent over-reliance on defensive solidity during his first seasons in England, but now he faces defensive questions of a different kind.
Stevan Jovetic was tipped on these very pages as Fiorentina's main attacking threat, and in the space of nine first-half minutes, he exposed the failings of a defence that has kept just one clean sheet on the road this season (and that was against League One side Leeds United).
Firstly, Jovetic was awesome. The 19-year-old Montenegrin ran the game from his split-striker position, picking up possession between Liverpool's midfield and defence, and wreaking havoc with his movement and creativity. Suddenly a defence that has always looked so organised, began to look terrifyingly susceptible to stealth and pace.
His first goal was about intelligence and ruthless finishing, as he stayed onside smartly to latch onto Cristiano Zanetti's pass and confidently beat Pepe Reina one-on-one.
His second was about instinct and technique, adjusting his feet in an instant to steer Juan Manuel Vargas' cross-cum-shot inside Reina's near post at pace. Liverpool simply never recovered.
But if Jovetic's decisive contribution showcased the talent and class that flows through the youngster's veins, it also highlighted worrying weaknesses in a defence that has looked decidedly shaky all season.
Even before the first goal, both Martin Skrtel and Jamie Carragher had looked troubled, both aerially and technically. One poor Skrtel header afforded Vargas a free volley at goal - which he ultimately shanked towards the corner flag.
It is becoming a trend; it was the Slovakian's misguided intervention which allowed Geovanni to briefly draw Hull City level at Anfield on Saturday.
For the first goal, the Reds' offside trap failed, with Emiliano Insua a good two yards behind their centre-backs. Jovetic was clever, but Insua made his life much easier.
The Reds had, prior to tonight, conceded just one goal (Geovanni's) from open play this season, with their set-piece defending coming under intense scrutiny.
But it would be take just nine minutes for Jovetic to lengthen Fiorentina's lead, and double the lingering doubts - particularly over Skrtel.
It was his header which, with Johnson better placed to clear behind him, fell to Vargas on the left edge of the Liverpool box. It was he who allowed Jovetic to get across him to apply the finishing touch. Johnson may well come in for slight criticism of his own for a lack of a solid shout, but there is little doubt the Slovakian could have done better.
The mistakes were not limited to the defence, of course, especially in the first half. Lucas Leiva and Fabio Aurelio, a makeshift central midfield pairing if ever there was one, failed to dominate their energetic Viola counterparts, whilst further forward there was little to enjoy from Fernando Torres, Steven Gerrard or Yossi Benayoun. Fiorentina were dominant in the opening period, and fully merited their lead.
A half-time pep talk from Benitez - he said afterwards that "everything was wrong in the first half" - livened up Liverpool, but still, the defence looked suspect.
Insua was given a torrid time by the lively, but not particularly special, Marco Marchionni, whilst Skrtel will spend tonight shielding himself from Jovetic-shaped ghosts, no question. The only reliable outlet tonight was, again, Pepe Reina, who is looking more and more like the best 'keeper around at the moment, certainly on form.
Fiorentina were excellent, especially in the first half, but with Rafa having banked on defensive solidity for so long, he now must find a way to plug the worrying gaps that are appearing in his back line. Does there need to be a change in philosophy, personnel, or both?
With Daniel Agger making his return for Liverpool's reserve side at Manchester City, Benitez will soon have a formidable and highly-rated asset call upon to bolster his defensive ranks.
Judging by the standards being set this season, he will not have to work too hard to get his place back.