It was a simple thumb on a stopwatch button that decided the outcome of close finishing races when motorcycle grand prix racing started back in 1949 on the Isle of Man. Today the thumb has been made redundant as modern technology decides what the eye or the stopwatch cannot - the winner of some of the closest finishes in the history of the sport.

Who knows if modern technology would have changed the result of some of those races from previous eras, but it is certain that technology has been needed to decide the winners in some classic battles over the last few years.

This season has been exceptional for those close finishes, as two encounters moved into the top ten finishes of all time. The fantastic battle at Brno last month, when Valentino Rossi beat Sete Gibernau to the chequered flag in the Czech Republic Grand Prix by just 0.042secs was the seventh closest finish of all time while, three weeks earlier, the Spaniard had reversed the positions when he won the German Grand Prix at the Sachsenring by the margin of just 0.06secs. Incredibly, that was only the tenth closest finish in the 54-year history of grand prix racing.

Camel Pramac Pons star Max Biaggi has been involved in some tight decisions in his 19-year career at the top. Two years ago, the four times 250cc world champion was involved in one of the truly great 500cc battles of all time. It was the day that his great rival Rossi clinched his first 500cc world title at Phillip Island in Australia, but Biaggi - aided by the Honda Pons duo of Loris Capirossi and Alex Barros and current team-mate Tohru Ukawa - was pushed to very limit around the magnificent Australian circuit. At the finish of 27 truly amazing laps, Rossi beat Biaggi by just 0.013secs, and the first four riders were separated by just 0.714secs. A massive 2.8secs covered the top nine.

It's rather fitting that, in the year that he lost his battle with cancer, that Barry Sheene has become the star of that top ten. Not only has he been involved in the closest finish of all time, but also makes three appearances.

The last British 500cc world champion typically won his very first 500cc grand prix in the closest ever finish recorded in the 500cc/MotoGP class. That was in the Dutch TT at Assen in 1975, when Sheene beat 15 times world champion Giacomo Agostini over the line, although the record books could not separate them on time. Today, they probably would have been separated but, 29 years ago, that thumb on the stopwatch button was not quick enough to ascertain the gap. It was left to the eyes, the oldest form of deciding races, to award Sheene victory.

Sheene's other appearances in the top ten came when he was beaten to the line by his great rival Kenny Roberts in the 1979 British Grand Prix at Silverstone. They were separated by just 0.03secs. It was the first motorcycle grand prix ever to be televised live in Great Britain and the race, the finish and the antics of the two riders as they fought it out, did much to increase the popularity of the sport - and Sheene in particular.

His third top ten appearance came at the little known Karlskoga circuit in Sweden. The 3.157km track staged just two 500cc grands prix in 1978-79 and Sheene won them both. In 1978, he beat Dutchman Wil Hartog by just 0.05secs, which was the eighth closest finish of all time.

The legendary Mick Doohan makes two top ten appearances but, to his disgust, both are when he lost races. The Australian five-times champion was beaten by his Honda team-mate Alex Criville at Brno in 1996 by 0.002secs. It was a commentators nightmare as Criville stalked Doohan throughout the 22-lap race before pulling alongside him on the line. It was only modern technology that picked the winner.

The ninth closest finish also involved Doohan but, once again, he was ruled second. It was in Barcelona, in the middle of his marvellous 1992 run of results that made him look a certain world champion until the infamous crash at Assen, not only cost him his first world title, but almost his career. In Spain, he was beaten in the race by 0.057secs by American Wayne Rainey, who went on to clinch his third world title in the last round that year at Kyalami in South Africa.

Rainey was involved in another top ten finish when he was beaten by fellow American Kevin Schwantz in a fabulous German Grand Prix race in 1991 at the ultra-fast Hockenheim circuit.

Two more American world champions complete the top ten, sharing fifth place with Roberts and Sheene. Freddie Spencer, the only rider to win 250cc and 500cc championships in the same season, beat four times world champion Eddie Lawson at the frighteningly fast Salzburgring in Austria by just 0.03seconds.

The day of the thumb and the stopwatch may be over, but those close finishes just keep on coming. Who knows, we may be looking at more top ten nominees in the final five races of the year, starting in Rio on Saturday.