BENEVENTO, Italy (AP) " The slopes of the Mount Vesuvius volcano will likely decide the Giro d'Italia winner.
Friday's final uphill finish also could be Lance Armstrong's last chance to meet his pre-race goal of winning a stage. The seven-time Tour de France champion began the race riding in support of teammate Levi Leipheimer. But now that Leipheimer is sixth and out of contention, Armstrong can try to move up from 12th place.
Denis Menchov of Russia enters the 19th leg with a 26-second lead over Danilo Di Luca in the overall standings.
"I expect a hard day tomorrow," Menchov said after he and the other leaders, including Armstrong, finished in the main pack in Thursday's 18th leg, 3 minutes, 57 seconds behind stage winner Michele Scarponi of Italy.
The serpentine Vesuvius climb is 8 miles and comes at the end of an already undulating 102-mile stage that takes riders along the hairpin curves of the scenic Amalfi coast.
"It's an important stage, maybe the most important of this Giro," Di Luca said. "It's a serious climb."
Vesuvius is best known for its eruption in A.D. 79 that buried the ancient city of Pompeii.
"It's not any different from other climbs, but the history is important," Menchov acknowledged.
Armstrong appears nearly back in form after 3 1/2 years of retirement and a broken collarbone in March. The Texan launched a failed solo attack in Wednesday's uphill finish to Blockhaus, and finished directly behind defending Tour champion Carlos Sastre.
Astana team manager Johan Bruyneel suggested Armstrong would be more astute in his strategy Friday.
"I think tomorrow he needs to find where his place is amongst all the strong climbers after three weeks of climbing," Bruyneel said. "I think he should try to be in the front."
Armstrong is 12:17 behind Menchov, but Bruyneel estimates he would be in better position if he hadn't slowed to help Leipheimer in the race's toughest stage to Monte Petrano on Monday.
"He's top 10," Bruyneel said. "Now let's see if he moves up a little bit in that top 10."
Armstrong could also gain positions in the short individual time trial that concludes the race in Rome on Sunday. He stopped speaking to the media nearly two weeks ago, apparently upset over the fallout of a rider protest in Milan that he helped orchestrate.
Scarponi won Thursday's stage in a sprint after a long breakaway. An Italian with the Diquigiovanni team, he was timed in 4 hours, 7 minutes, 41 seconds over the 113-mile leg from Sulmona to Benevento.
Felix Rafael Cardenas of Colombia finished second and Danny Pate of the United States was third, both with the same time as Scarponi.
"It was a pretty comfortable sprint," Scarponi said. "I even had time to zip up my jersey."
In March, Scarponi won the weeklong Tirreno-Adriatico race for his first victory since serving an 18-month ban for involvement in the Spanish doping scandal Operation Puerto.
Pate rides for the Garmin-Slipstream squad, which has now had three runner-up finishes and two third-place results.
"No one even remembers who got second in stage 18. No one even knows what stage it is today," Pate said. "It's just all about the win. We were close. We rode a really good race; it just didn't work out. Not much you can do about it."
Menchov's Rabobank team confirmed it has been contacted by Austrian authorities for questioning in a blood doping case. Menchov said he has nothing to hide from prosecutors.
"I don't have any problem," he said. "If they want to, after the race we'll find a time."