Amid the rather less glamorous surroundings of Glasgow's Scotstoun's leisure centre yesterday, there was an episode of big brother's little brother, as both men's younger siblings, named Marko and Christian respectively, battled for a place in round two of the AEGON GB Pro Series.
These are the hard yards of making a career in the world tennis ranks, and both men's hopes live on, with Marko coming through 6-3, 2-6, 6-4 against the giant Richard Becker of Germany, and Christian prevailing 6-3, 7-6 (8-6) against qualifier Scott Griekspoor of the Netherlands.
"Myself and Marko were laughing about that actually, thinking how funny it would be if we both got drawn against each other in the first round here," said Harrison, an 18-year-old from Florida ranked 501 in the world who drew a fair old crowd when he partnered his brother at the US Open. "I think if we both win one more then we could meet up but that is still a long way away because we both have tough opponents."
The family resemblance was also apparent in the case of the younger Djokovic, a man who appears to have reached accommodation with persistent unflattering comparisons with his older brother. Marko, now 21, is the middle son of three Djokovic siblings – amazingly some reckon 17-year-old Djordje may be the best of the bunch – and while his hair is a little longer, his double faults more regular, and his languid frame betrays the fact he is rather less intense than his brother, there is that same easy power and uncanny acquaintance with the geometry and geography of a tennis court.
This was Marko's first visit to Glasgow, although the young Novak appeared at this tournament back in 2006, and the world No.660 simply seemed happy enough to be playing and winning again after a career which has been ravaged by illness and injury.
"I have played professional tennis since I was 17 but I've had a lot of problems," Marko said. "I had mono (nucleosis) like Robin Soderling, which they say is from kissing but I think I got it from a bottle of water. I had that for one year then a wrist problem then a hip problem and in 2011 I didn't play for the whole year.
"It is very tough when you are young to have so many injuries but now there are no injuries and I can concentrate on tennis," he added.
"Hopefully I can rise up the rankings, you never know, but, in my opinion, I have the quality to do this. The injuries were really tough but I've come back stronger and I'm happy with my life. Maybe I can get top 100 or top 50 but even if I stay at 600 then I am still happy."
One man unable to progress yesterday was the 17-year-old Scottish wild card Jonny O'Mara. The unranked O'Mara can at least take heart in having extended Mathieu Rodrigues, the world No.443 from France, to three sets before going down 7-5, 2-6, 6-3 in front of the watching Leon Smith, the head of men's and women's tennis at the LTA.