While Djokovic has a firm grip on top spot, there will be a new number two on March 15 in Russian Daniil Medvedev, who will climb one place to his career-best ranking to replace Nadal, who has not played since the Australian Open due to a back injury.
Marcin Matkowski and Mariusz Fyrstenberg beat fourth seeds Mahesh Bhupathi and Mark Knowles 6-4, 6-2 in the final of the Madrid Masters.
Marin Cilic beat unseeded German Michael Berrer 6-4, 6-7, 6-3 on Sunday to win the Zagreb Indoors tournament for the second successive year and clinch his fifth career title.
Rohan Bopanna became the oldest ATP Masters 1000 champion when he and his Australian partner Matt Ebden claimed the men's doubles crown
Simona Halep will take over as the new number one in the WTA world rankings after progressing to the China Open final with a dominant 6-2 6-4 victory over Latvia's Jelena Ostapenko in Beijing on Saturday.
Nick Kyrgios was given a warning for taking too long to return Tsitsipas's serve
A summary of sports events and sports persons, who made news on Tuesday
For all his renowned mental strength it was psychological exhaustion that made Rafael Nadal consider skipping the season-ending ATP World Tour finals this year, the 14-times grand slam champion said on Tuesday.
Serbia have been drawn in Group B alongside Spain, South Korea and Canada.
The former world No.1 doubles pair upset fourth seeds Mark Knowles of Bahamas and Daniel Nestor of Canada in the semi-finals of the ATP Masters.
Unheralded Igor Kunitsyn upset former world number one Marat Safin 7-6, 6-7, 6-3 in an all-Russian Kremlin Cup final to clinch his maiden title.
The Serbian had to save two set points in the first set before finding his groove to reach his 10th title clash in Rome and remain on course to win his 36th ATP Masters 1000 crown and overtake Rafael Nadal on the all-time list.
Rohan Bopanna and Aisam-ul-haq Qureshi missed out on capturing their second ATP title of the season after losing the fiercely fought final of the St. Petersburg Open to Daniele Bracciali and Starace Potito, at St.Petersburg.
The second seeds cruised through the second set after a tense opener
Roger Federer's late bid to secure his customary place in the season-ending ATP World Tour finals began with a routine opening round win over Adrian Mannarino in his home town tournament in Basel on Monday.
American teenage sensation Coco Gauff progressed to her maiden WTA final as she eased past Germany's Andrea Petkovic 6-4, 6-4 at the Linz Open on Saturday. The 15-year-old Gauff became the youngest player to reach a WTA final since Czech Republic's Nicole Vaidisova won the Tashkent Open in 2004, also aged 15.
Zverev had surgery on torn ligaments in his right ankle this month after he was forced to retire from his French Open semi-final against Rafael Nadal.
Russian qualifier Daniil Medvedev stunned home favourite Kei Nishikori in Tokyo on Sunday, winning the final of the Japan Open 6-2, 6-4 in just over one hour.
The Serbian top seed won a fourth successive title at the All England Club to take his overall Grand Slam tally to 21.
Andy Murray battled past Romanian qualifier Marius Copil 6-3, 6-7(7), 6-4 at the European Open in Antwerp on Friday to reach his first singles semi-final in two years.
Top seed Janko Tipsarevic of Serbia lived dangerously before making the final with a confident 6-1, 6-4 triumph over qualifier Go Sodea of Japan in the semi-final of the ATP Tour $450,000 Chennai Open Tennis championship on Saturday.
Rafael Nadal delved deep into his seemingly inexhaustible reserves of willpower on Saturday to fight off Andy Murray in a three-hour classic and reach the final of the ATP World Tour Finals for the first time.
American Andy Roddick has booked his place at the World Tour Finals with four weeks of the season remaining, the ATP said on Tuesday.
'It's pretty amazing to get the call from the Spanish king'
To mark 20 years of Ivanisevic's win, the ATP tweeted, his road to victory.
Leander Paes and Stanislas Wawrinka shocked 2014 Wimbledon champions Vasek Pospisil and Jack Sock 7-6(4), 3-6, 10-3 to make it to the doubles quarter-finals at the ATP Masters Western and Southern Open, in Cincinnati, on Tuesday.
Wawrinka splits with long-time coach Norman
Carlos Alcaraz heralded the changing of the guard in men's tennis as he ended Novak Djokovic's long reign at Wimbledon
India's Rohan Bopanna and Ramkumar Ramanathan registered a resounding straight-set win to cruise into the doubles semi-finals but it was the end of the road for compatriot Sania Mirza and her Ukrainian partner Nadiia Kichenok, in Adelaide, on Friday.
Rohan Bopanna and Prakash Amritraj crashed out in their respective men's singles semi-final matches at ATP Challenger Series tournaments being simultaneously played in England and the United States.
Norrie's semi-final opponent will be another American, fourth-seeded Tommy Paul, who crushed Stefan Kozlov 6-3, 6-1 in an all-US matchup.
Veteran Leander Paes brushed off the disappointment of Rio Olympics as he and his German partner Andre Begemann made it to the final of the ATP Winston-Salem Open beating Swede Robert Lindstedt and Pakistan's Aisam-ul Haq Qureshi in a close encounter.
Daniil Medvedev handed Novak Djokovic his first loss of the year, defeating the world no. 1 6-4, 6-4 in Dubai.
Roger Ferdrer came up with a solid all-round display to beat world No 1 Rafael Nadal 6-4, 6-3 in the final and win the Shanghai Masters on Sunday.
World No 1 Novak Djokovic maintained his perfect tournament record and advanced to his fifth China Open final with a 6-3, 6-4 victory against Andy Murray on Saturday.
Defending champion Andy Murray and ATP finals hopefuls Mikhail Youzhny and Fernando Verdasco all made surprise early exits from the Valencia Open on Wednesday. World number four and top seed Murray fell 6-2, 3-6, 6-2 to Argentine Juan Monaco in the second round, while world number 10 Youzhny pulled out at the start of the day with a back problem.
Former world number one Rafa Nadal wasted a match point as he slipped to a surprise semi-final loss to Austrian Dominic Thiem on his beloved clay at the Argentina Open on Saturday.
World No 1 Novak Djokovic ended Kei Nishikori's impressive debut at the ATP World Tour Finals with a 6-1, 3-6, 6-0 semi-final victory at the O2 Arena on Saturday.
While Federer and Nadal will look to reignite the flair and fight they showed to reach last year's final, 2018 could have a different script at play.