Vitosha, playing in a professional league for the first time, are eighth in the standings on four points from three games.
At 54 years, two months and 12 days, Borisov, who resigned from government in February during nationwide protests in the EU's poorest country, had secured a place in the Bulgarian record books, according to local statisticians.
Borisov, wearing number 13, was cheered by the Lokomotiv stadium crowd in the Sofia district of Nadezhda every time he touched the ball during his 54 minutes of action.
In 2011, Borisov triumphed in the Bulgarian fans' player of the year poll after collecting 44 percent of the votes with then-Manchester United striker Dimitar Berbatov coming second with 24 percent.
However, Borisov urged organisers to annul the poll, describing it as a protest vote.
"This vote is not a signal that Borisov is the best player but that the Bulgarian football needs reforms and a new policy," he said.
- Sports & Recreation