Maybe the Centre Court spectators were saluting Novak Djokovic’s opponent by saying his name. Maybe they were booing Djokovic, trying to rattle him. The 24-time Grand Slam champion was sure it was the latter — and he let everyone know he was not happy about it. Djokovic easily beat 15th-seeded Holger Rune 6-3, 6-4, 6-2 in just over two hours Monday night to reach the Wimbledon quarterfinals, then made sure to get a message across to those fans he thought were against him. Rune’s supporters at various tournaments often will stretch out his last name, saying, “Ruuuuuune!” — which sounds rather similar to “Boooooo!” — and that happened again Monday.