Novak is one win away from defending his season finale title after he beat Stanislas Wawrinka 6-3, 6-3 in 84 minutes at the O2 Arena.
Nole recorded his 70th win of the season, beating no.8 seed Richard Gasquet 7-6 (5), 4-6, 6-3 at the Barclays ATP World Tour Finals.
Defending champion beat Juan Martin del Potro 6-3, 3-6, 6-3 and improved to a 2-0 record in Group B. He will meet Stanislas Wawrinka in Sunday semi-finals.
Nole beat no.5 seed Roger Federer 6-4, 6-7 (2), 6-2 in his first round-robin match in Group B at the O2 Arena in London.
Novak remains at no.2 spot in the latest ATP rankings released on Monday, November 4.
Novak came back from a break down in both sets to beat defending champion David Ferrer 7-5, 7-5 and win his 40th career trophy.
Novak will play against defending champion, Spaniard David Ferrer (3), for his second BNP Paribas trophy (Sunday at 15.00 CET).
The world’s biggest indoor tournament begins on Monday, November 4, at the O2 Arena in London, and will be played until November 11.
Novak is through to the BNP Paribas Masters last four with a 6-1, 6-4 win over Stanislas Wawrinka. He goes on to face no.5 seed Roger Federer.
Novak came back from a set down to beat no.13 seed, American John Isner, 6-7 (5), 6-1, 6-2 in one hour and 50 minutes.