John McEnroe has blasted the decision to allow 30-year-old former world number one Marcelo Rios to play on the seniors tennis circuit.
McEnroe finished runner-up in his qualifying group in London
McEnroe lost his a quarter-final showdown with the Chilean at the Masters at the Albert Hall on Friday.
He said: "It's totally wrong. Over the years they've bastardised the thing - 35 seemed a reasonable age (limit).
"In seniors golf they set the age limit at 50 and kept it. They haven't changed the rules to let some 40-year-old in."
Rios reeled off 25 straight wins after joining the tour earlier this year.
McEnroe opened his Masters campaign with a hard-fought victory against Sweden's Anders Jarryd on Thursday night but lost 7-6 7-5 to Cedric Pioline on Friday