Novak Djokovic, the top seed of US Open 2020 (and world #1 as of the start of the tournament) was defaulted from his 4th round match against Carreno Busta after hitting a line judge with a ball. This reminds me of when in 2009 also at the US open, Serena Williams was given a point penalty when down a match against Kim Clijsters point for verbally abusing a line judge. Serena was the second seed in that tournament, but the top remaining seed at the moment of the incident.
Has a top seed - male or female - in any grand slam ever been defaulted/disqualified from a match?