Players observe a moment of silence for Brad Drewett at Madrid Open

The ATP's and WTA's top players led a moment of silence before the start of play at the Madrid Open on Sunday in remembrance of ATP executive chairman and

The ATP's and WTA's top players led a moment of silence before the start of play at the Madrid Open on Sunday in remembrance of ATP executive chairman and president Brad Drewett, who died on Friday after a battle with motor neurone disease.

The tribute was lead by the ATP Big Four -- Novak Djokovic, Andy Murray, Roger Federer and Rafael Nadal -- with a number of WTA players, including No. 1 Serena Williams, Petra Kvitova, and Sabine Lisicki, also in attendance to pay respects. A moment of silence was also observed before the finals at the Portugal Open and the BMW Open in Munich.

"Obviously, Brad wasn't just the president of the ATP but was a player himself, a board member," Federer said. "He's given so much time and effort to the ATP, and I think this is really what we will try to honor in a small way today. Then obviously, I think many more players got to know him through his position in the last one and a half years.

"He was always very nice to work with," Federer continued. "Very honest. Very nice. Gentle. I've really enjoyed every step of the way working with him. For me, it was hard seeing him not be the same anymore toward the end physically. But we can only appreciate what he's done for us and what he did until the last moment he really possibly could. That will never go away. I'm sure that the ATP and the players will come up with something for the legacy of Brad Drewett. It's very important."

Tennis world reacts to Brad Drewett's passing, pays tribute

(Photos via Getty Images)