Australia were in a rush on the opening day of the Davis Cup finals group phase on Tuesday with Jason Kubler and Alex de Minaur paving the way for a 3-0 win over Belgium.

Newcomer Jason Kubler battled past 134th-ranked Zizou Bergs 6-4, 1-6, 6-3 in the opening Group C tie in Hamburg, Germany.

Trailing 1-3 in the third set after dropping the second, 97th-ranked Kubler reeled of five consecutive games to earn the first point for Australia. 

"I'm over the moon that I was able to deliver today but we may not have been in this position if it were not for Jason Kubler who came out on his debut and pulled a rabbit out of the hat," said de Minaur.

"He played with passion and pride and showed everything that Davis Cup is about. He got the win which gave us a 1-0 lead which I thought was huge."

De Minaur got the winning point for the 28-time Davis Cup champions after beating David Goffin 6-2, 6-2 in one hour and six minutes.

Goffin, ranked 62, a Davis Cup finalist in 2015 and 2017, has never beaten 22nd-ranked Minaur in their four meetings.

Matthew Ebden and Max Purcell teamed up in the doubles to see off Sander Gille and Joran Vliegen 6-1, 6-3.

The Germans open their Group C campaign against France on Wednesday before also facing Belgium and Australia.

In Group A, Argentina play Sweden on Tuesday with Canada and South Korea in action in Group B and Kazakhstan vs. Netherlands in Group D.

In the last-16 group phase, nations play two singles matches and then a doubles in a best of three format.

The top two teams in the Davis Cup group matches progress to the last eight in Malaga from November 22 to 27.