Australia's Olympic hopes have received a double blow with cyclist Simon Gerrans officially ruled out of Rio with a broken collarbone and Lleyton Hewitt's withdrawal as coach of the men's tennis team for "personal reasons".

Gerrans, considered a strong medal prospect in the road race event, underwent surgery over the weekend on a broken collarbone suffered during a crash at the Tour de France.

Facing a battle against time, he held out hopes of competing in Rio on the tricky, cobble-stoned course, but Australia Olympic Committee officials were informed on Sunday morning that his attempt to ride at a third Olympics was now over.

Gerrans flew from France to Barcelona late last week and was operated on over the weekend.

After he woke up, he posted on Twitter an X-Ray of his collarbone, showing off the new screws in place. He tweeted: "My new hardware... The surgery went as well as we could hope. Now it's time to put a plan in place."

The Orica-BikeExchange veteran crashed heavily during Stage 12 of the Tour. He kept on riding but was later forced to leave the race when diagnosed with a broken collarbone.

There was much hope Gerrans — renowned for being a tough competitor — would fight back and compete in Rio. 

Cycling Australia chief executive Nick Green told Fairfax Media on Friday: "Before we have all the information on where Simon is at, he's a member of the Olympic team. Unfortunately, he's a member of the team with a broken collarbone." 

Australia's chances in Rio now rests in the hands of Richie Porte, Rohan Dennis and an as-yet-unnamed rider.

Meanwhile, Australia's tennis team has been thrown into further turmoil with Tennis Australia applying at the 11th hour for Mark Draper to replace Hewitt as coach of the men's team.

Already dogged by the ugly public feud involving chef de mission Kitty Chiller that led to the withdrawals of top-ranked players Nick Kyrgios and Bernard Tomic, Hewitt's departure is another blow.

The reason proffered is "personal reasons", but the timing is curious because Hewitt had been desperate to earn a wildcard entry to play doubles following the withdrawals of Kyrgios and Hewitt.

Hewitt was weighing up the prospect of partnering with John Peers — who he was forced to play alongside in the Davis Cup loss to the US at Kooyong in March — but the idea has been torpedoed. 

Beneficiary: Chris Guccione.

Under messy tennis quota rules at the Olympics, players ranked in the top 10 can partner with any other player within the top 1000.

Because Peers has recently dropped seven spots to 17th in the ATP's doubles world rankings, it means Tennis Australia had no choice but to opt for Chris Guccione. 

The likely men's squad will be John Millman, Thanasi Kokkinakis, Peers and Guccione.