The Spaniard, who has slipped to world number 672, said he was feeling much better than a year ago but added that he cannot have long-term goals just yet.
Coco Gauff battled past Elina Svitolina in the Auckland Classic final on Sunday to retain her title.
Maria Sharapova will return to tournament action at the Brisbane International next month
Rafael Nadal announced on Sunday that he would be opening his 18th season as a professional at the Brisbane International in January.
Australia's Lleyton Hewitt delighted his home fans when he battled to a typically gutsy 6-1, 4-6, 6-3 victory over Swiss top seed Roger Federer in the Brisbane International final on Sunday.
Japan's Kei Nishikori overcame Daniil Medvedev in the Brisbane International final on Sunday for his first ATP title in nearly three years and the 12th of his career.
Venus Williams has pulled out of the upcoming Brisbane International after suffering a 'setback' in training
The 23-times Grand Slam champion looked a completely different player from the person who smashed her way into the semi-finals of the doubles with Caroline Wozniacki on Wednesday but managed to do just enough to beat the 86th-ranked McHale.
World No 1 Serena Williams showed plenty of rust in her first competitive outing of the year ahead of the Australian Open, but battled through to defeat Andrea Petkovic in straight sets at the Brisbane International on Tuesday.