Rafael Nadal has endured a turbulent few weeks after slipping to defeats in Monte Carlo and Barcelona last month before being hit by a stomach bug on Sunday.
Miami Open: Hsieh Su-Wei battled back from being a set down to beat Naomi Osaka 4-6, 7-6 (7/4), 6-3.
Del Potro, the 2009 US Open champion and Auckland winner, beat Ferrer 6-4, 6-4 to continue his strong form from the end of last season.
Rafael Nadal needed all his trademark grit against Alexander Zverev, 19, dubbed "the future of tennis", and his superior fitness told as he ground out a thrilling 4-6, 6-3, 6-7 (5/7), 6-3, 6-2 win
Sumit Nagal went down fighting to Marc Lopez in the penultimate match, while Ramkumar Ramanathan was convincingly beaten in the last singles rubber as Spain completed a 5-0 whitewash over India in the Davis Cup World Group play-off
Marc Lopez defeated Sumit Nagal 6-3, 1-6, 6-3 to give Spain 4-0 lead over India in Davis Cup World Group playoff, before David Ferrer defeated Ramkumar Ramanathan 6-2, 6-2 to complete a 5-0 whitewash. Catch Davis Cup highlights here
Leander Paes and Saketh Myneni went down fighting to Rafael Nadal and Marc Lopez in the doubles tie on Day 2 of the 2016 Davis Cup World Group play-off between India and Spain. Catch Davis Cup highlights here
Ramkumar Ramanathan's spirited response to the challenge by Feliciano Lopez kept the 4,000-strong fans excited, Saketh Myneni was blown away by world number 13 David Ferrer, the 2013 French Open finalist
Feliciano Lopez defeated Ramkumar Ramanathan 6-4, 6-4, 3-6, 6-1 in the first match of the day. David Ferrer then thrashed Saketh Myneni in straight sets 6-1, 6-2, 6-1 to give Spain 2-0 lead over India in World Group play-off. Get all the highlights of India vs Spain here
Rafael Nadal has pulled out of Spain's Davis Cup World Group playoff tie vs India due to a stomach bug. He will be replaced by Feliciano Lopez in the singles rubber.
The best David Ferrer came close to winning a Major was when he reached the 2013 French Open final but lost that summit clash to Davis Cup teammate Rafael Nadal
Rafael Nadal has been crucial in Spain's victorious Davis Cup campaigns in the past (2004, 2008, 2009 and 2011)
Leander Paes said budding tennis players of India should come to DLTA for watching and learning from Rafael Nadal, who is in the Capital for Spain's Davis Cup tie against India
Rafael Nadal and David Ferrer will play for Spain in the Davis Cup World Group play-off against India at the RK Khanna Tennis Complex in the Capital
Leander Paes argued that it's only a myth that players with the calibre of Rafael Nadal and David Ferrer can be worn down by heat as they are the marathoners of world tennis who can slug it out for hours in tough conditions
Spain will play against India in World Group Davis Cup play-off in New Delhi from September 16 to 18
Rafael Nadal, who was upset by France's Lucas Pouille in the US Open, will be joined by 13th-ranked David Ferrer for singles duty with Feliciano Lopez and Marc Lopez slated for doubles
India have drawn Spain in the Davis Cup World Group play-offs at home, with the prospect of 14-time Grand Slam winner Rafael Nadal turning out for his country