Roger Federer, wife Mirka and their twin daughters were spotted at Zurich airport picking up some visiting friends - Gwen Stefani, Gavin Rossdale and their sons.
Gwen, 44, and Gavin, 48, have made no secret of the fact their family recently visited Switzerland.
They have both posted holiday snaps on Instagram - including a lovely shot of Gwen breastfeeding their youngest son, Apollo.
But until now it was not known that as well as seeing the sights, they also caught up with their old friends, the Federers.
Gwen and Gavin had all three of their sons in tow - Kingston, eight, Zuma, five, and six-month-old Apollo.
Roger and Mirka's five-year-old twin daughters, Myla Rose and Charlene Riva, were there to greet the boys, but their younger brothers, two-month-old twins Leo and Lenny, weren't taken on the airport trip.
On Monday Gavin completed the Ice Bucket Challenge with Jessica Alba and Nicole Ritchie, after the trio were nominated by Gwen.
Zuma wasn't officially part of the challenge, but he too took a soaking while sat on his father's knee.
Gavin nominated Cash Warren, Roger Federer and Dave Grohl - who has just announced the birth of his third child.
Zuma nominated Kingston - who in turn nominated his dog - although Zuma felt Apollo would have been a better target!
Participants of the Ice Bucket Challenge make a donation to the ALS Association in America, or the Motor Neuron Disease Association and Macmillan Cancer Support in the UK.
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