(Corrects spelling of Firmin and his nationality in third para)
By Alasdair Fotheringham
MADRID, Sept 15 (Reuters) - American Chris Horner, nicknamed 'Grandpa' by his peers, created more than one landmark when he won the Tour of Spain on Sunday at the age of 41.
Horner is the first rider from the United States to win cycling's third Grand Tour. Andy Hampsten won the Giro d'Italia in 1988 and Greg LeMond took the Tour de France in 1985.
At almost 42, Horner is also the oldest Grand Tour winner by a hefty margin. The father-of-three, who lives in Bend, Oregon, outstrips the Vuelta's oldest previous winner, Tony Rominger of Switzerland in 1994, by nine years, and he is almost six years older than the Tour de France's most senior winner, Firmin Lambot of Belgium in 1922.
"How long will I continue racing? I have no idea. At least two or three years would be good," the RadioShack rider told reporters before the start of Sunday's final stage.
"If my legs are still turning the same way, I will continue.
"But I hope people appreciate everything I've done, it's so complicated to get to this level. This is the hardest victory of my career so far," added Horner, a professional of 19 years, who said he did not yet have a contract for 2014.
"The problem is my age. If I was 20, it would be very different, 50 different teams would be offering me a job."
Born in Okinawa, Japan, where his father was serving in the U.S. army, Horner began working in garages and building sites as a teenager in order to buy his own bike. He turned professional for the small U.S.-based Nutra Fig squad and spent a decade mostly with minor American teams.
In 2005, aged 33, he took part in his first three-week stage race, the Tour de France, finishing 33rd, and then raced for two years as a team worker with Belgian squad Lotto.
Horner's breakthrough in Grand Tour racing came when he finished ninth in the Tour de France in 2010, the same year that he took his first major stage race, the Tour of the Basque Country.
In 2011, after winning the biggest race in the United States, the Tour of California, a bad crash and subsequent abandon put him out of the Tour de France, although the following year at RadioShack Leopard, his current team, he finished 13th.
This year started badly for Horner, with a knee injury wiping out almost the first half of the season. However, a victory in the toughest mountain stage of the Tour of Utah in August and second place overall showed that the American had rising form for his one Grand Tour of the season, the Tour of Spain.
"For many his victory is a surprise but not for me and I've been working with him for five years now," Horner's sports director Jose Azevedo told El Mundo newspaper on Sunday.
"He's come to this race rested because (before Utah) he had not been racing for several months and at this point in the season that makes a big difference."
Famous for his love of hamburgers and chocolate bars and his upbeat temperament, Horner's nickname in the peloton of the Tour of Spain is 'el abuelo' - 'Grandpa'
"I've always been under-rated or not quite given the leadership when I think I should have had it for different reasons," Horner said earlier this week.
"Maybe (because of) my age, or maybe I'm not brass enough, but there's always something in my career that made people think I'm not as good as I am." (Editing by Clare Fallon)