Thanks for the info Aileen.
Zverev the Elder played Andy in 2003 and 2005 in Futures on hard courts, Andy won both times.
Can't believe his ranking is as low as #653 though, but maybe he hasn't played much in the last couple of years because his ranking as plummeted since 2013 He got as high as #45 in June 2009 though. Oh - and he's a leftie, so Andy will need to practise with brother Jamie.
If Tennis Explorer is right, then the match will be at noon on Thursday, presumably Munich time.