Experts are concerned about the players' fitness with two big tournaments been scheduled back-to-back
The Spaniard is one Grand Slam away from levelling Federer's tally of 20 titles.
The 33-year-old had been an unstoppable force in Spain's pulsating semi-final against Britain on Saturday.
Murray was earlier rested for Britain's group match against Kazakhstan
Great Britain won their match against the Netherlands at the World Cup of Tennis
The Davis Cup Finals will now be played in a World Cup format with 18 national teams competing for glory
Murray, who inspired Britain to the 2015 Davis Cup title, will line up alongside his older brother Jamie, Dan Evans, Kyle Edmund and Neal Skupski.
The Serbian is supportive of the changes but wants a debate on the timing of the World Cup of Tennis.
New proposals to overhaul the Davis Cup into a World Cup-style competition have drawn a mixed response from the tennis world.
Nadal has played a part in 3 of Spain's 5 Davis Cup wins and is very motivated to make a comeback in 2018 should Spain progress further in the competition.
Although they are not his goals at the moment, Roger Federer has refused to rule out the possibility of competing in the Davis Cup and the 2020 Tokyo Olympics.
Kyrgios is known for stepping up whenever he faces a big name.
Bedene claims he has not spoken with Evans since he made those remarks on his nationality.
Hewitt also believes Kyrgios is more talented than he ever was.
Spain crashed out of the competition after defeat to Serbia at the quarter-final stage.
Kyrgios helped Australia advance to the semi-final of the Davis Cup.
Great Britain eliminated after 4-1 defeat to Yannick Noah's team in Rouen.
Jamie Murray and Dominic Inglot lose in four sets to Nicolas Mahut and Julien Benneteau in Rouen.
Lucas Pouille and Jeremy Chardy hand hosts comfortable lead in Rouen.
Djokovic's elbow injury saw him withdraw from the recently concluded Miami Open.
World number one forced out of Davis Cup tie against France but could play Match for Africa 24 hours later.
GB captain Leon Smith names the same side that beat Canada in the previous round.
Elbow tear means world number one is expected to miss quarter-final clash in Rouen.
Djokovic dropped to number two in the rankings at the end of 2016.
Andy Murray, Tomas Berdych and Boris Becker have also praised Federer's performance in Melbourne.
The 17-year-old shot to fame after hitting an umpire with a ball on Sunday.
French official Arnaud Gabas struck in the eye to force dramatic conclusion in Ottawa.
Andy Murray and Milos Raonic not involved in Ottawa this weekend.
World number one could yet be reinstated for tie in Ottawa on 3-5 February.
Andy Murray led Britain to glory in the tournament in 2015.