Earlier, Serbia played 2 matches in Group F. They won Austria with a score of 3-0 but then lost to Germany with a score of 1-2. Therefore, Serbia can only rank 2nd in this table with a record of 1-1, the match difference is 4-2. (Novak Djokovic won his two single battles against Dennis Novak and Jan-Lennard Struff).
At the Davis Cup 2021, 6 teams in the table with 2 second teams with the best achievement will reach the quarterfinals. With a 1-1 achievement, the match difference is 4-2, the game difference is 9-6, Serbia is the second name with the second excellent achievement, just enough to reach the quarterfinals. They are ranked in Spain thanks to the difference of the game (9 wins, 6 losses compared to 9 wins and 7 losses).
Thus, 8 names reached the quarterfinals of the Davis Cup 2021 were RTF (Russian delegation), Kazakhstan, the United Kingdom, Croatia, Italy, Germany, Sweden and Serbia.
In the quarterfinals, Serbia will meet Kazakhstan. This is a team with not very prominent players such as Alexander Bublik, Dmitry Popko, Mikhail Kukushkin, Aleksandr Nedovyesov or Andray Golubev but won the first place in Group B when he won both Sweden and Canada.

In addition to Djokovic, Serbia also has names such as Dusan Lajovic, Filip Krajinovic, Miomir Kecmanovic and Nikola Cacic. They have 4 players in the top 100 men's singles but no players specialize in the squad.
In addition to Serbia, only RTF and Italy are owning 4 players in the top 100 in the world. In particular, the RTF delegation is a heavy candidate for the championship. In the quarterfinals, this team will meet Sweden.