[6] In the official Japanese Thoroughbred rankings for 2017 Mozu Ascot was given a rating of 107, making him the 42nd best three-year-old on turf, fourteen pounds behind the top-rated Rey de Oro.

[7] Christophe Lemaire was Mozu Ascot's regular jockey for the 2018 season which began on 25 February at Hanshin when the colt was beaten a neck by the five-year-old mare Diana Halo when favourite for the Grade 3 Hankyu Hai.

In his next two starts he was runner-up to Sungrazer in the Grade 2 Yomiuri Milers Cup at Kyoto on 22 April and then ran second for the third time in a row when beaten by Daimei Fuji in the Listed Azuchijo Stakes over 1400 metres at the same track on 27 May.

Mozu Ascot however, having raced on the inside rail, angled to the right in last 100 metres before threading his way through a gap between the leaders, overtaking Aerolithe in the final strides and winning by a neck.

[10] After a break of well over four months Mozu Ascot returned on 27 October at Kyoto when he started odds-on favourite for the Swan Stakes but was beaten a nose by the five-year-old Lord Quest.

Despite his defeat he was made the 2.4/1 favourite for the Grade 1 Mile Championship at the same track on 18 November but finished thirteenth of the eighteen runners, four lengths behind the winner Stelvio, after being unable to obtain a clear run in the straight.

[13] On 2 June he started at odds of 34/1 as he attempted to repeat his 2018 victory in the Yasuda Kinen and finished sixth of the sixteen runners behind Indy Champ beaten just over two lengths by the winner.

He ended his season in the Mile Championship on 17 November when he started a 18.9/1 outsider and finished fourteenth of the seventeen runners, beaten seven and a half lengths by the winner Indy Champ.

After settling behind the leaders and turning into the straight in sixth place, Mozu Ascot made a forward move to take the lead 200 metres from the finish and drew away to win by two and a half lengths from K T Brave.

[16] Mozu Ascot was scheduled to contest the Doncaster Handicap in Australia but quarantine measures imposed after the COVID-19 outbreak meant that he remained in Japan and was dropped back to 1200 metres on turf for the Takamatsunomiya Kinen at Chukyo on 29 March.

After the summer break Mozu Ascot returned in the Mile Championship Nambu Hai at the National Association of Racing's Morioka Racecourse and finished second to Arctos, beaten a neck by the winner.