John Terry and Anton Ferdinand met at Wembley as the Chelsea captain's Football Association disciplinary hearing over allegations he racially abused the QPR defender started.
Ferdinand gave evidence to the independent panel at the hearing Monday, with Terry in attendance to hear the case against him.
Central defender Terry, who dramatically announced his retirement from international football on Sunday, effectively accused the FA of forcing his hand after the governing body pressed on with charges that he racially abused Ferdinand in October.
Terry, who has always denied using a racist slur against his opponent, was found not guilty in a criminal case relating to the incident in a London court in July.
Ferdinand was at Wembley all morning, leaving shortly before midday, while Terry -- who will reportedly return on Tuesday -- left near 3pm local time (1400GMT).
The case could last most of the week.
England manager Roy Hodgson said on Monday that he had "reluctantly" accepted John Terry's decision to call time on his international career, as the centre-back contested a Football Association racism charge.
Despite the controversy, Hodgson picked Terry in his squad for the European Championship in June and wanted to have the 31-year-old involved in England's bid to qualify for the 2014 World Cup in Brazil.
"I'd like to thank John Terry for his commitment to the England team since I became manager," said Hodgson. "I am of course disappointed to lose a player of John's international experience and exceptional ability.
"I have enjoyed a good relationship with John during my time as England manager and I reluctantly accept his decision. I can also confirm that he had the courtesy to call me prior to the announcement of his retirement from the England team.
"I'd like to wish John well for the future with Chelsea."
In a separate statement, the FA thanked Terry for his England service.
"Following his announcement that he is retiring from the England team, the FA would like to thank John Terry for all of his efforts with the national team over the past decade," read a statement from the FA.
"During his 78 appearances, John has always given his full commitment to the team."
Former England captain Terry, who is to continue playing for European champions Chelsea, on Sunday hit out at the FA for putting him in what he felt was an impossible position.
"I feel the FA, in pursuing charges against me where I have already been cleared in a court of law, have made my position with the national team untenable," he said in a statement.
But FA general secretary Alex Horne told Sky Sports on Monday: "It's a personal decision. I don't see how we've made it untenable; they're two very separate processes.
"That's a very different process from our England procedures."
Meanwhile, former Chelsea manager Avram Grant criticised the FA for taking the action against Terry.
"Nobody thinks that John Terry is a racist so the FA need to leave it," Grant told the BBC.
"John likes to fight and he's very passionate about the national team so I was surprised," Grant added of Terry's decision to quit England football.
"But he's not a child. He knows what he's doing."
The criminal action had to prove Terry's guilt beyond reasonable doubt but the judge ruled the prosecution had not proved their case to that standard.
Terry had hoped his courtroom acquittal would be the end of the matter as he FA's rule book states that the result of any previous legal action concerning the same matter will "presumed to be correct".
Terry admitted in court he used a racial slur against Ferdinand but said he was merely repeating what he believed Ferdinand had accused him of saying.
The panel, who gave Liverpool striker Luis Suarez an eight-match ban for racially abusing Manchester United defender Patrice Evra last season, said just using racist language was enough to constitute a breach of FA rules.