McManus qualified for the inaugural Indian Open, beating amateur Sydney Wilson 4–1 in qualifying. He was then beaten 1–4 in the last 64 by Zhang Anda. McManus followed up this result by qualifying for the International Championship in beating Darren Cook 6–0. He then defeated local wildcard Zhou Yuelong 6–5, coming back from 2–4 down. In the last 64 he produced the shock of the tournament by beating defending champion Judd Trump 6–5, having been 3–4 down. However he was defeated 4–6 by Ryan Day in the following round. At the 2013 UK Championship, McManus defeated Joel Walker 6–5, winning the match on a respotted black, before losing to Michael Holt 4–6 in the last 64. McManus reached the last 16 of the German Masters, defeating Jak Jones 5–1 in qualifying. At the Tempodrom he defeated Peter Ebdon and Jack Lisowski, both by 5–2 scorelines, before being himself beaten 2–5 by Michael Holt.