Ivan Lendl said it felt as if he had "never stepped away" after watching Andy Murray mark the resumption of their coaching partnership with a win.
Lendl was in the players' box as world number two Murray beat Nicolas Mahut 7-6 (10-8) 7-6 (7-1) to reach the second round at Queen's Club.
"Andy and I have talked over the last few years," Lendl, who reunited with the Scot on Sunday, told BBC Sport.
"We've stayed in touch, and as you know, we parted on good terms."
Murray won the Olympics, the US Open and Wimbledon during his original spell with the Czech-born American, until Lendl decided in March 2014 that he no longer wished to spend sufficient time on tour.