Vaelncia - Argentina's Juan Monaco shocked defending champion and home favourite David Ferrer 7-5, 1-6, 6-3 on Saturday to set up a final clash against Spain's Marcel Granollers in the Valencia Open.
Monaco, ranked 41, also broke Ferrer's winning run in his home city event of 14 wins stretching back to 2007.
After breaking Monaco's serve as early as the second game world number five Ferrer looked a likely finalist again in an event he won in 2008 and 2010.
However despite Ferrer racing into a 3-0 lead, Monaco showed a fighting spirit he may need in early December when the two could meet in the Davis Cup Final, to fight back and win the first set.
Ferrer found more consistency to take the second, only dropping one game, and looked to be on his way to victory with an early break in the third, but Monaco broke straight back to set up the decisive set nicely.
The Argentine then took advantage of a Ferrer double-fault to break again in the sixth game and go 4-2 ahead. From then on he looked comfortable as he held his serve twice to advance.
His opponent on Sunday also produced a shock semi-final win to reach his second successive final here after losing in straight sets to Ferrer last year.
Granollers ousted Argentine Juan Martin Del Potro 6-4, 7-6 (7/4) in 1 hour 52 minutes to reach the final.
Barcelona-born Granollers, ranked 34, has again had a spectacular week here and will be confident of adding to two career titles - Houston in 2008 and Gstaad this year.
On Friday, Granollers beat number three seed Gael Monfils of France in the quarter-finals and Saturday's straight sets victory came against an in-form Del Potro who had not dropped a set on his way to the semi-finals.
The defeat is a blow to Del Potro, currently ranked tenth in the battle to qualify for the end of year ATP World Tour Finals in London later this month.
Del Potro must now reach the final at next week's Paris Masters to qualify.
After that he must prepare to return to Spain with Monaco for the Davis Cup final in Seville from December 2-4, where Ferrer and a rested Rafael Nadal are likely to await him.