Monaco's annual big-name signing has finally touched down on the Riviera, enjoyed a whistle-stop tour of the casinos and seen his new side limp to a 1-1 draw against bottom club Strasbourg.
Vieri penned an 18-month contract with Monaco after agreeing to a free transfer from AC Milan, where he endured an unhappy six months. They are the twelfth club of a journeyman who, apart from a six-year stint at Inter Milan, has made a point of changing club at least once a year.
In seven breathless years between 1992 and 1999, he was on the books of (deep breath): Torino, Pisa, Ravenna, Venezia, Atalanta, Juventus, Atlético Madrid, Lazio and Inter Milan.
Wherever Vieri has travelled, he has always scored goals, and Monaco supporters will hope he can settle in quickly and have the same impact that Morientes did during loan from Real Madrid in 2003-4.
Frozen out at the Santiago Bernabeu, the Spaniard reignited his career in a sensational spell at Monaco. He scored 19 goals, nine of them in the Champions League, where he spearheaded Monaco's expedition to the final and knocked out hapless Madrid in the process.
At the pinnacle of his career, Vieri easily outshone Morientes, boasting superior technique, power and finishing. But this is a 32-year-old version of a former great, who sunk to fourth in the AC Milan pecking order behind Andriy Shevchenko, Alberto Gilardino and Filippo Inzaghi and has scored just once in eight Serie A outings this season.
Where Morientes arrived desperate to prove his worth to the Galáctico-obsessed Real Madrid president Florentino Perez, Vieri has a different motivation - the World Cup.
In 2002, Italy controversially lost to South Korea after falling victim to some dreadful refereeing decisions. But the conspiracy theorists would do well to remember that it would have been done and dusted by then had Vieri not missed a virtual open goal in the last minute of normal time.
If some have forgotten that howler, Vieri certainly has not, and craves the chance to atone for his error. Yet with a host of other forwards in contention (Francesco Totti, Alberto Gilardino, Alex Del Piero, Luca Toni, Vincenzo Iaquinta and Antonio Cassano to name just six), he has rightly determined that he needs to start playing and scoring, pronto, if he wants to get any use out of those 'Teach Yourself German' tapes.
However, the welcome party may fall short of an all-Italian love-in. Guidolin was reportedly unhappy at the deal, because Vieri is a difficult character who will not settle for a place on the bench. Guidolin has denied the rumours, but did admit the signing was 'a gamble'.
Meanwhile, Milan midfielder Gennaro Gattuso wondered aloud whether Vieri would much fancy 'playing in front of about a thousand people' at the Stade Louis II. 'Quite a change from the San Siro,' he added, helpfully. Although perhaps not so different from Vieri's Juventus days.
It is a typical Monaco deal - no fee, with the hefty wage bill softened by the principality's tax-haven status. While the rest of Ligue 1 is subject to standard (i.e. swingeing) French taxes, Monaco's foreign players do not pay income tax, giving the club an automatic advantage of nearly 50% when attracting stars from abroad.
Yet Monaco have been at pains to emphasise how little they are paying Vieri, who will reportedly pocket a mere five million euros over the course of his 18-month contract only months after Inter paid him nine million just to leave the club. Just how will he get by?
With Di Vaio and Vieri's arrival balanced by the departures of Patrice Evra and Maicon, the Stade Louis II has been a flurry of transfer activity, typical of the restlessness throughout the top half of the table brought on by Lyon's dominance. It is impossible to imagine any of the chasing pack mounting a serious challenge, with just four points separating second-placed Bordeaux from Rennes in tenth.
Far from creating excitement and rivalry, this parity has a numbing effect, as positions fluctuate faster than Diego Maradona's weight, and the whole exercise ends up feeling rather pointless.
A lack of firepower has proved a stumbling block for many of the pretenders. Three of the top eight - Bordeaux, Saint-Etienne and Monaco - have scored one goal per game or fewer, while only Pauleta of PSG has found the net more than eight times in the opening 21 rounds of matches.
On Wednesday, Lyon pulled off yet another comeback as they beat Marseille 2-1 at the Stade Gerland. They have now gone behind in eleven matches, but lost only once; this ability to get themselves out of jail is what separates them from everyone else.
So it is hardly surprising to see so many strikers popping their heads through the January transfer window. Lens have picked up Pierre-Alain Frau on loan from the champions, with Marseille grabbing Mickaël Pagis from Strasbourg.
St. Etienne have secured the services of Portuguese international Helder Postiga on loan, while Nantes are pinning their hopes on a Kenyan - 20-year-old Dennis Oliech.