By Rory Carroll
NEW YORK (Reuters) - Former NFL player Colin Kaepernick received an enthusiastic welcome from fans at the U.S. Open's showcase match between Serena and Venus Williams on Friday night when he was shown raising his fist on the big screen.
The 30-year-old, who was a quarterback at the San Francisco 49ers for six years and sparked a national debate when he knelt during the national anthem during the 2016 NFL season to protest racial injustice and police brutality, smiled at the cheers.
Former 49ers safety Eric Reid, who protested alongside Kaepernick and who like his former team mate remains unsigned, also received a warm reception when he was also shown raising a fist at a packed Arthur Ashe Stadium.
"Every athlete, every human and definitely every African American should be completely grateful and honoured by how Colin and Eric are doing so much for the greater good," Serena Williams told reporters following her win.
"They really use their platform in ways that is really unfathomable, so I feel like they obviously have great respect from a lot of their peers, especially other athletes and people who are looking for social change."
Kaepernick and Reid have both filed collusion grievances against NFL owners and league over the fact that neither has been signed by any of the NFL's 32 teams since their protests spread around the league.
On Thursday, system arbitrator Stephen Burbank denied the league's request to dismiss the case, which means he found sufficient evidence for the case to continue and perhaps go to trial.
The protests of the national anthem have raised the ire of some NFL fans and U.S. President Donald Trump, who has said they disrespect the American flag and the military.
(Editing by Nick Mulvenney)