Miami, March 30 : The men's and women's singles quarterfinal clashes between Carlos Alcaraz-Taylor Fritz and Petra Kvitova- Ekaterina Alexandrova at the Miami Open on Wednesday night was postponed due to rain. The World No. 1, Alcaraz, who must successfully defend his debut ATP Masters 1000 title in Miami this week to remain atop the ATP Rankings, will continue his quest for the 'Sunshine Double' against Fritz on Thursday night now. On the other hand, the last remaining singles quarterfinal between No.15 seed Kvitova and No.18 seed Alexandrova never got started and will be also held on Thursday. Defending champion Alcaraz is aiming to become the youngest player to win the 'Sunshine Double'. If the Spaniard can defeat Fritz and go all the way, he will also remain at No. 1 in the ATP Rankings. Any slip up, however, and Novak Djokovic will return to the top. Chasing his 10th consecutive win, the Spaniard will look to maintain his level and overcome Top 10 star Fritz. The American is no stranger to the big stage, having lifted the trophy in Indian Wells last year. Fritz would rise to No. 6 in the ATP Rankings if he lifts his second ATP Masters 1000 crown on Sunday. Meanwhile, the last remaining women's doubles quarterfinal, pitting No.2 seeds American pair Coco Gauff and Jessica Pegula against No.6 seeds Australian-Belgian duo of Storm Hunter and Elise Mertens, was also interrupted and postponed as well. Hunter and Mertens lead that match 3-1 in the first set when rain played spoilsport. /IANS