He leads the men's seedings ahead of defending champ Roger Federer, with Bulgarian Grigor Dimitrov seeded third.
Williams reached the final of the mixed team event earlier this year with American compatriot John Isner to kick off a superb season where she won the Australian and French Opens and Wimbledon to take her grand slam singles haul to 21.
Andy Roddick beat impressive Japanese teenager Kei Nishikori 6-2, 6-4 in the second round of the San Jose Open.
Victory meant Nadal set the record for the longest Davis Cup winning streak in combined singles and doubles rubbers with 23 matches in a row.
Wimbledon's new head groundsman said on Thursday he is "100 percent happy" with the grass courts despite a string of players tumbling out of the tournament through injury.
Roger Federer began his latest quest for a 100th ATP title with a battling 6-4, 3-6, 6-1 win over Philipp Kohlschreiber in the first round of the Dubai Duty Free Tennis Championships on Monday.
US captain Patrick McEnroe said the duo would be joined by the world's top-ranked doubles pair, Bob and Mike Bryan. John Isner and Sam Querrey will travel with the team as practice partners.
Former partners Mahesh Bhupathi and Leander Paes started off their respective doubles campaigns on a winning note at the Legg Mason Classic.
Somdev Devvarman put up a strong fight before going down to world No 31 Fernando Verdasco, while Mahesh Bhupathi lost in the first round at the ATP China Open, in Beijing, on Thursday.
Andy Murray remained on course for a maiden Paris Masters title after the Briton saw off local favourite Richard Gasquet on Friday to reach the semi-finals with a 7-6(7), 3-6, 6-3 victory.
Top seed Andy Roddick beat Mardy in the quarter-finals of the San Jose Open but James Blake lost to Robby Ginepri.
Italian tennis player Marco Cecchinato has been banned for 18 months and fined 40,000 euros ($44,024) for match-fixing, the Italian tennis federation has announced.
Olympic and Wimbledon champion Andy Murray picked up where he left off in Rio by drubbing Argentina's Juan Monaco to take his place in the third round of the Western & Southern Open in Cincinnati on Wednesday.
IMAGES from matches on Day 9 at the French Open at Roland Garros
The success of the American women at this year's US Open is nothing else than a reward from the Williams sisters' inspiration
Novak Djokovic had to fight back from a set down to beat Thomaz Bellucci and reach the Italian Open quarter-finals.
Roger Federer gained a measure of revenge against Wimbledon nemesis Kevin Anderson, beating the South African 6-0, 6-4 at the Miami Open on Thursday to set up a mouthwatering semi-final against a player barely half his age.
'He can say what he wants, I don't have a problem with it. Does he show me the same amount of respect that most other players do? No, he doesn't, but that's the way he communicates these days'
As Real Madrid star striker Cristiano Ronaldo watched, the World No 4 Nadal went past Italian Bolelli to set up a quarter-final clash against 10th seed Grigor Dimitrov.
Defending champion Djokovic fired his 15th ace on match point to defeat Querrey but his serve had been an issue earlier in their second-round encounter.
Djokovic had his personal best winning sequence of 30 consecutive sets ended as Cilic played almost flawlessly aggressive tennis to draw first blood in a magnificent duel.
A summary of sports events and sports persons, who made news on Friday.
Seventh seed Wawrinka of Switzerland set up a third-round meeting with Bulgarian ninth seed Grigor Dimitrov after seeing off Argentine Juan Monaco 6-4, 6-1.
The 22-year-old Australian breezed past the 15-times Grand Slam champion in about one hour and 20 minutes.
The 21-year-old Coric came from two sets to one down to defeat the 20-year-old debutant Tiafoe 6-7(0), 6-1, 6-7(11), 6-1, 6-3 and finally subdue a remarkable fightback from the Americans, who had earlier levelled the tie 2-2 from two down.
World number one Serena Williams credited an on-court coffee for her recovery after she stormed back from a first set bagel to beat Italy's Flavia Pennetta in her opening match of the year at the Hopman Cup on Monday.
France will meet Serbia in the semi-finals of the Davis Cup after both finished off their last-eight ties inside two days on Saturday but Australia and Belgium were made to sweat.
Roger Federer survived a stern test from Spain's Roberto Bautista Agut to reach the Miami Open quarter-finals on Tuesday, while top-seeded Swiss compatriot Stanislas Wawrinka was eliminated on his birthday.
India's Somdev Devvarman notched up a stunning 6-3, 7-6 (7/4) victory over defending champion Alexandr Dolgopolov to advance to the pre-quarterfinals of the ATP 500 Citi Open in Washington on Tuesday.
The trick-shots, underarm serves and tirades at spectators are all part of the theatre, and the 'what will he do next?' lure puts bums on seats, in much the same way John Daly still draws a crowd in golf.
Novak Djokovic beat Tomas Berdych 7-6 (3), 7-6 (8) in the quarter-finals of the Paris Masters on Friday to claim his 20th consecutive win and stay on course for an unprecedented third title in a row at the event.
A few days after it appeared as though a Roger Federer impersonator had gatecrashed the 02 Arena, the Swiss great resumed normal service to outplay Kevin Anderson and reach the last four of the ATP Finals on Thursday.
The All England Club's medical rooms were overflowing as the third day of Wimbledon resembled a casualty ward with Rafa Nadal's conqueror Steve Darcis one of five players to withdraw injured before mid-afternoon on Wednesday.
Anderson's rock-solid belief was unshakeable, even when he faced a match point in the 10th game of the third set.
A clinical Roger Federer took a confident step towards a fourth Miami Open title on Wednesday, easing past 13th-seeded Russian Daniil Medvedev 6-4, 6-2 to book a spot in the quarter-finals.
The seventh-seeded Bulgarian advanced to his eighth ATP World Tour Masters 1000 quarter-final with a 6-3, 7-5 victory over Del Potro, who struggled with the intense heat in the closing stages of the one hour, 39 minute match.
Benoit Paire made a remarkable Davis Cup debut for France, outplaying Pablo Carreno-Busta 7-5, 6-1, 6-0 in the opening rubber of the World Group semi-final tie against Spain at the Stade Pierre-Mauroy on Friday.
The 16-year-old backed his aggressive backhand throughout the contest and went on to win 17 of his 23 points at the net to seal victory in 61 minutes.
Novak Djokovic spurred Serbia to a 3-0 win over neighbours Croatia in the first round of the Davis Cup on Saturday and they will be joined in the quarter-finals by an equally rampant France.
Rafael Nadal and Roger Federer will set aside their long-time rivalry when they play for Europe against the rest of the world in the inaugural Laver Cup tournament which starts on Friday.