"Brooklyn's idea?" - Kim Clijsters and Serena Williams react to Andy Roddick going rock climbing

Andy Roddick's recent rock climbing expedition drew reactions from his friends Serena Williams and Kim Clijsters. While Williams expressed her surprise, Clijsters wondered whether it was Roddick's wife Brooklyn Decker's idea.

Roddick took to social media earlier this week to post an image of himself as he went rock climbing.

"So we had a day," read the caption of Roddick's Twitter post.

Serena Williams, who is good friends with Roddick, was surprised to see the former US Open champion on a rock climbing expedition.

"Wow what ????" Williams replied to Roddick.

Meanwhile, Clijsters felt that rock climbing might not have been Roddick's idea.

"Brooklyns idea ?" Clijsters wrote.

Roddick is one of the most active tennis players, past or present, on social media, and often does not shy away from sharing his views on political and social issues.

Among the many wonderful tributes to Williams during her recent retirement tour at the US Open swing were several from Roddick, who often spoke about Williams' contributions and how they transcend tennis. Roddick also highlighted that both Venus and Serena Williams are fun to be around and the lighter side of their personalities often gets neglected.

"I don’t think people see enough of the lighter side of Venus and Serena. They’re such a joy to be around when they’re not in ‘go mode.’ We’ve celebrated people’s competitiveness over the years with the greats of all time. Unfortunately, I don’t think we’ve given them the benefit of the doubt to have those kinds of same competitive moments," Roddick said during an interview with Fansided.

"One of my idols and favorite people" - Andy Roddick on Jimmy Connors

Roddick (L) and Connors during a practice session at the 2007 Australian Open

Meanwhile, American tennis greats Andy Roddick and Jimmy Connors will share the stage during an upcoming event organized by the Andy Roddick Foundation. Roddick will be the moderator of the event, to be held from November 3-5, and will have a fun chat with his former coach Connors. Roddick expressed his excitement at joining Connors, calling the 109-time ATP title winner 'one of his idols' and favorite people.

"Come see us :) @JimmyConnors @theARFoundation. I’ll be the moderator for the convo w one of my idols, former coach, and favorite people," Roddick wrote on Twitter.

Connors was Andy Roddick's coach for almost two years before resigning in 2008. He joined Roddick's team after the 2006 Wimbledon Championships and Roddick reached the US Open final that same year, under Connors' tutelage. He also won the Davis Cup for the United States while Connors was his full-time coach.