After a short (but oh, so long) off-season, tennis is back! Here's our review of everything that's happened so far in the first three days of the ATP Cup.1:50-4:56: Tournament withdrawals including Djokovic, Thiem, Rublev and Karatsev.Day 14:56-7:30: Spain ?? v Chile ??: PCB defeats a decent Challenger-level player in Alejandro Tabilo.7:30-8:39: Spain ?? v Chile ??: RBA thrives in perfect conditions for him, Cristian Garin continues to struggle on hard-courts.8:39-11:27: Serbia ?? v Norway ??: Casper Ruud continues to impress on hard-courts with another win versus Dusan Lajovic.11:27-12:51: Georgia ?? v Argentina ?? and Poland ?? v Greece ??: A bland tie that saw Argentina and Poland come out on top.Day 212:51-18:23: Russia ?? v France ??: Ugo Humbert shows why he has such a healthy top-10 record in defeating Daniil Medvedev.18:23-20:41: Russia ?? v France ??: Roman Safiullin saves the day for Russia in the singles and the doubles.20:41-25:38: Italy ?? v Australia ??: Jannik Sinner demolishes 2020 Australian Open doubles finalist, Max Purcell, whilst Alex De Minaur turns his 2021 season around with a phenomenal returning performance against Matteo Berrettini.25:38-27:57: Italy ?? v Australia ??: The established Aussie pairing of John Peers/Luke Saville prove too much for Matteo Berrettini/Simone Bolelli.27:57-31:15: USA ?? v Canada ??: USA win their tie against Canada thanks to a brilliant first match of the season from Taylor Fritz.31:15-37:08: Germany ?? v UK ??: Though Alexander Zverev wins an impressive match against Cam Norrie, the Brits take the tie in the doubles.Day 337:08-40:30: Spain ?? v Norway ??: Casper Ruud and RBA play one of the matches of the tournament so far.40:30-42:06: Serbia ?? v Chile ??: Chile win their first ATP Cup tie after Lajovic suffers cramp against Garin.42:06-44:44: Poland ?? v Georgia ??: Hubert Hurkacz’s reactive returns make things difficult against Aleksandre Metreveli but Poland inevitably pull through against Georgia.44:44-47:04: Argentina ?? v Greece ??: Diego Schwartzman plays a stellar match against an under par Stefanos Tsitsipas.