London - Boris Becker has defended Alexander Zverev's decision to skip the Davis Cup to play a series of exhibition matches against Roger Federer.
The German No 1, defending his ATP Finals title in London, will miss the season-ending Davis Cup finals in Madrid next week.
Instead he is scheduled to take on Federer in four lucrative exhibition matches in Latin America.
But Zverev will be in Australia in January to take part in the inaugural ATP Cup after nominating former world number one Becker as team captain.
"Look, he's old enough to make his own decision," Becker said at the ATP Finals on Thursday.
"He decided amongst a few other players when the decision was made to change the Davis Cup format and to have it in one week... not to participate."
"He's always played for Germany whenever I ask him," added Becker, who is head of men's tennis for the German federation.
"He played in the first round against Hungary in Frankfurt the beginning of the year, and he did his bit and he's won his points.
"He was very excited to play at the ATP Cup, as well. What he does in his off time, he's his own man. We were all our own boss. What he chooses to do or not to do between the end of the ATP Finals and the beginning of 2020 is his choice."
The Davis Cup's new 18-team format has replaced the former World Group.
The nations have been split into six three-team groups, with the winners and two best runners-up advancing to the quarter-finals.
Defending champion Zverev beat world number one Rafael Nadal in his ATP Finals opener earlier this week but defeat against Stefanos Tsitsipas left his title hopes in the balance.