"All in all we are pleased with the progress he has made," Roger Williams told reporters on Friday outside London's Cromwell hospital where Best is in intensive care with a bowel infection.
"He is a little better than he was last night, but he is still a very sick man," he added.
Best, 59, who has been in intensive care since 2 October, has had an alcohol problem for much of his adult life and underwent a liver transplant in 2002 after years of heavy drinking.
Day by day
Williams refused to speculate on whether Best was now on a stable path to recovery. "We go on treating day by day."
Best's son Calum went to his father's bedside on Thursday afternoon after several British newspapers ran front-page stories saying the former player was close to death.
"He is still a very sick man"
Dr Roger Williams,
Best's agent Phil Hughes was quoted in The Daily Telegraph as saying the Belfast-born player's condition was "as serious as it can get".
Best was regarded by many as the greatest player to come from the British Isles.
He had a dazzling but short career at Manchester United, winning the European Cup in 1968 when he was named European Footballer of the Year.
Nicknamed "the 5th Beatle", Best is widely seen as the first superstar soccer player, attracting frenzied media coverage as much for his colourful private life as his on-field talent.
His career nosedived when he left United and he has been dogged by alcohol problems since.