"Some of the important points I didn't play well, that's for sure," Haas said.
"You can't get much of a rhythm when he's serving pretty well or you don't allow yourself to get the return back in play. The quickness, the little steps are definitely not there yet.
"It was a little bit of a struggle, no question about it. He played well when it counted."
Frenchman Benoit Paire became the second seed to fall, slumping to a 6-3 6-4 loss to Roberto Bautista Agut of Spain - a player ranked nearly 50 places below him.
And former world No8 Marcos Baghdatis will also be on an early flight to Australia after being ousted by unheralded American Steve Johnson 7-5 6-7 (3) 6-4.
Johnson was only included in the main draw as a "lucky loser" from qualifying after Frenchman Gael Monfils withdrew on the eve of the tournament.
With the match carried over from Tuesday after rain forced the abandonment of that night's late session, he was scheduled to be back in action last night with a second-round match against fourth seed Kevin Anderson of South Africa.
German Philipp Kohlschreiber advanced through to the third round with a straight-forward 6-4 6-2 win over Argentina's Horacio Zeballos.
After a tricky first-round assignment against Spaniard Pablo Carreno Busta, Kohlschreiber was pleased with his clinical display yesterday.
"Today was a new day. I played a great match and didn't make many mistakes. I served well, very clever with the wind.
"It's tricky in the wind. Overall I played a very clever and great game," said Kohlschreiber.
In yesterday's late afternoon match, third-seeded American John Isner beat Lukas Lacko 7-6(1) 3-6 6-2.APNZ