Venus Williams made her Grand Slam debut in May 1997, while Naomi Osaka was born in Oct 1997.
Any others?
Identifying this is problematic for some sports. For our purposes, highest level will exclude junior or reserve/second team appearances, while for soccer, a first team club appearance is sufficient, no need for international caps. Cricket, Test, ODI, not first class. Tennis, first appearance in a singles GS main draw.
American sports would be an actual appearance in NFL, MLB, NBA game etc.
Many fathers-sons pairings in MLB: Bobby and Barry Bonds, Ken Griffey Sr and Jr, Felipe and Moises Alou, Jose Cruz Sr and Jr, Sandy and Roberto Alomar, and Cecil and Prince Fielder, to name only a few.
This is fairly common in snooker where you have older players like Ronnie O’Sullivan playing against teenagers. Ray Reardon only retired (from snooker) at age 60 so may have played against players who could have been his grandchildren.
Gordie Howe played on a line with his two sons for the Houston Aeros of the WHA in 1974. He played until 1980, ending his career with the Hartford Whalers. In his last season there was only one player on his team (Bobby Hull) who was born when Howe made his NHL debut.
ETA - there were 3 players on the 1979-80 Whalers born before Howe made his NHL debut in 1946.
Bobby Bonds started his career in '68, Barry was born in '64.
Griffey Sr. started in '73, Jr. was born in '69.
Cecil Fielder started in '85 and Prince was born in '84.
Only the Griffeys meet the conditions of this thread, in that they actually played together or against one another. None of those other examples meet that criteria.
The only other example in baseball history of a father and son playing together are Tim Raines Sr. and Jr. I cannot think, to be honest, of any other examples of father and son playing against each other.
In the 1980 All Star game Howe (b. 1928, age 52) played against Wayne Gretzky (b. 1961, age 19). Howe was 33 and had been playing in the NHL for 15 years when Gretzky was born.
I would say these are notable events, but probably relatively common (of the order of happening several times a year) in cricket and football. In both sports it is not unusual for players to make their debut at age 17/18, so it only requires another player to have maintained a career of that length, making them 35+. This is a pretty normal age for goalkeepers and cricketers.
Phil Mickelson is still a World Class Golfer, ranked #33 in the current OWGR. He won a World Golf Championship event last March. He will be 49 yrs old in June.
Players ranked higher than him than were born after his first win in 1991 include Spieth, Thomas, Schauffele, Rahm, DeChambeau, all in the Top 20 of the OWGR.
George Blanda played in the NFL until age 48. His first year in the league was 1949, and his last was 1975.
In that final season, he was playing with a number of teammates who had been born after he had made his debut in '49 with the Bears, including his fellow specialist, punter Ray Guy, starting fullback Mark van Eeghen, tight end Dave Casper, and backup quarterback David Humm.
While this isn’t specifically about a professional athlete, does anyone remember the 41-year-old gymnast who competed in the 2016 Olympics for Uzbekistan? She had a son who was older than some of her teammates.
It’s common in pro wrestling–Johnny Valentine teamed with his son, Greg Valentine (though Greg was billed as Johnny’s brother so as to kayfabe Johnny’s age). Dusty Rhodes teamed with his son Dustin, Bill Watts was the booker when his son, Eric, worked for WCW, Nick Patrick wrestled as Assassin #3 teaming with his father, Jody Hamilton as Assassin #1, Jake Roberts and Sam Houston both worked under their father, Grizzly Smith in Mid-South, Brian Lawler worked with his dad Jerry Lawler, Fritz Von Erich teamed with various combinations of his sons, Tommy Gilbert teamed with his son Eddie, etc…