Petter Northug and Dario Cologna were supposed to have a two-man duel at the Sochi Olympics to establish which one should be called the world's best cross-country skier.
Because of injuries and illness, however, no one knows quite what to expect from the sport's two biggest stars next month - making these Olympics unusually unpredictable on the men's side.
Northug and Cologna have combined to win the last five overall World Cups, but both have had their Olympic season disrupted by health issues. Northug, the Norwegian double gold medalist in Vancouver four years ago and a nine-time world champion, had a stubborn virus at the start of the season that set back his preparations. He has only won one World Cup race so far - a 10-kilometer stage on the Tour de Ski - but says he's back to full fitness and will be a threat again in Sochi.
''I'm way ahead of where I should be (fitness wise),'' Northug said after the recently concluded Norwegian championships. ''The plan is to really top my form for Sochi. ... I won't be satisfied unless I get a gold.''
However, Northug relies largely on his explosive sprinting ability, which for years made him a big favorite in any mass-start race, and it remains to be seen whether that trademark burst of speed is still there.
Cologna, who in Vancouver became the first Swiss cross-country skier to win an Olympic gold, is an even bigger question mark. Cologna hasn't competed at all on the World Cup circuit this season after tearing a ligament in his right ankle in November, but won two races at the Swiss championships this month and said he is also finding his form.
''I've definitely taken a step forward compared to a week ago,'' he said.
On the women's side, these Olympics should be another duel for supremacy between Norway's Marit Bjoergen and Justyna Kowalczyk of Poland.
Bjoergen dominated the Vancouver Games, winning three golds but losing a tight sprint finish to Kowalczyk in the concluding 30K race. Kowalczyk has been the most consistent World Cup skier, winning four of the last five overall titles - finishing second to Bjoergen in 2011-12 - but has often seen herself beaten by the Norwegian at the major championships.
Expect both to climb the podium several times again in Sochi - the only question is in which order.
Here are five things to know about the cross-country skiing events in Sochi:
NORWEGIAN DOMINANCE: As always, Norway is likely to top the cross-country medals table, on both the men's and women's side. Northug and Bjoergen both have a handful of teammates capable of fighting for medals and will each anchor a relay team heavily favored for gold. Martin Johnsrud Sundby leads the men's overall World Cup standings ahead of countryman Chris Andre Jespersen. On the women's side, Therese Johaug heads a quartet of Norwegians atop the overall standings. With four individual events for both men and women, don't be surprised to see at least one Norwegian podium sweep.
NEW GENERATION: This could well be the last Olympics for both the 33-year-old Bjoergen and the 31-year-old Kowalczyk, and there is a host of younger women looking to supplant them atop the sport. Johaug has been seen as Bjoergen's heir apparent in Norway, but the list of challengers also includes her teammates Astrid Jacobsen and Heidi Weng, along with Sweden's Charlotte Kalla. This could be the time for one of them to brand herself the next big star.
AMERICAN FIRST?: No American has ever won a gold medal in cross-country skiing at the Olympics. On Feb. 11, Kikkan Randall has a very good chance of becoming the first. Randall is one of the favorites in the women's individual freestyle sprint, an event she specializes in and has won 10 times on the World Cup circuit.
RUSSIAN HOPES: Host nation Russia will be hoping to improve on its performance in Vancouver, when its cross-country skiers earned one gold and four medals in total. Nikita Kriukov surprisingly won the individual sprint four years ago but that event switches to freestyle this time rather than his preferred classical style. However, the team sprint is classical, and Russia will be among the favorites there. In addition, Alexander Legkov has been a consistent World Cup performer this season and should be fighting for medals in the long-distance races, as should teammate Maxim Vylegzhanin.
HEALTHY HELLNER?: Marcus Hellner came away with two golds in Vancouver, winning the 30K skiathlon and then leading Sweden to victory in the men's relay, but his form is another big question mark ahead of Sochi. Hellner has also struggled with illness this season and has not had a single World Cup podium finish. If he's not at his best, traditional power Sweden's best chance for a gold may be Johan Olsson, the reigning 50K world champion.