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Alcaraz swept aside the 2022 Indian Wells champion 6-4 6-2 in a lopsided Miami Open contest which lasted only 79 minutes, with the Spaniard breaking Fritz in the opening game of both sets.
Both players hit 20 winners, including 11 each on their respective forehands, but Fritz almost doubled Alcaraz' unforced errors count (28-13).
The 19 year-old was impressive from the baseline and overwhelmed Fritz in the end. The American only won 38 per cent on his second serve.
Alcaraz, who won the Indian Wells title a fortnight ago, remains on track to become the eighth male to win the Sunshine Double (Indian Wells and Miami), with Roger Federer the last to achieve that in 2017.
The Spaniard would join Federer (2005, 2006, 2017), Novak Djokovic (2011, 2014, 2015, 2016), Andre Agassi (2001), Marcelo Rios (1998), Pete Sampras (1994), Michael Chang (1992) and Jim Courier (1991) in achieving the Sunshine Double.
Alcaraz will take on Italian 10th seed Jannik Sinner in the semi-finals, after the duo faced off in the Indian Wells last four a fortnight ago, with the Spaniard winning in straight sets.
In-form Daniil Medvedev progressed to the semi-finals with a 6-3 7-5 victory over American qualifier Chrstopher Eubanks, who had enjoyed a dream run in Miami.
Medvedev has a 27-3 record this season and will pursue a fifth straight ATP Tour final when he takes on compatriot Karen Khachanov in the semi-finals.
Khachanov, who made this year's Australian Open semi-finals, defeated Francisco Cerundolo 6-3 6-2 in 76 minutes.