In November, Nadal had announced the withdrawal from the ATP World Tour Finals citing a knee injury, which also forced him to subsequently pull out of Paris Masters.
The Spaniard was then scheduled to return to court in the season-opening Brisbane International starting on January 1, but he withdrew from that as well.
19-time Grand Slam champion Roger Federer is placed as second seed while Bulgaria's Grigor Dimitrov and Germany's Alexander Zverev have been named third and fourth seed, respectively, the Daily Express reported.
For women's singles event, Caroline Wozniacki is seeded second Garbine Muguruza followed by Elina Svitolina, Venus Williams, Karoliina Pliskova, Jelena Ostapenko, Caroline Garcia, Johanna Konta, CoCo Vandeweghe.
Meanwhile, 2017 Australian Open champion Serena Williams opted out of the competition, saying that her preparations had fallen just short of what she needed to be competitive after giving birth in September.
It should be noted that the seedings have gone largely according to the ATP world rankings.
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