"I guess that's where 10 years in Auckland helps you," he said.
Kohlschreiber quickly wrapped up the first set 6-2. But Carreno Busta, who was voted the most improved player on the ATP tour last year, having climbed 650 positions from 715 to 65 in 2013, fought back strongly in the second, playing some impressive forehand volleys to take it to a decider.
After Kohlschreiber's tough centre court battle, sixth-seeded Frenchman Benoit Paire by contrast had a more straightforward first-up encounter, blitzing Poland's Michal Przysiezny 6-4, 6-2 in 49 minutes.
The only seed to fall in the opening round was Robin Haase of the Netherlands, who went down to Spain's Guillermo Garcia-Lopez in a match that went to a third-set tiebreak.
Rubin Statham's appearance in the main draw of the singles lasted just over an hour, with the Kiwi No 1 easily accounted for by Slovakian Lukas Lacko 6-3, 6-1.
Rain forced an early end to last night's evening session, creating a scheduling nightmare for organisers today. Drizzly conditions interrupted the first match of the evening between American qualifier Bradley Klahn and Daniel Brands of Germany. Klahn won the first set 7-5, but trailed 2-4 when the match was stopped. They will resume on centre court today, with play at Stanley St to start at an earlier time of 10am.
Last night's late game between wildcard Marcos Baghdatis and American Steve Johnson was also postponed and will be pushed to an outside court. The respective winners of the two matches will play twice today.
Top results
*Guillermo Garcia-Lopez (ESP) bt 8-Robin Haase (NED) 4-6 7-5 7-6(4)
*5-Philipp Kohlschreiber (GER) bt Pablo Carreno Busta (ESP) 6-2 3-6 7-5
*Roberto Bautista Agut (ESP) bt Daniel Gimeno (ESP) 6-1 3-6 6-4
*Q-Donald Young (USA) bt Federico Delbonis (ARG) 7-5 6-2
*Q-Lukas Lacko (SVK) bt WC-Rubin Statham (NZL) 6-3 6-1
*2-Julian Knowle (AUT)/Marcelo Melo (BRA) bt Tommy Haas (GER)/Andre Sa (BRA) 6-1 6-4
*6-Benoit Paire (FRA) bt Michal Przysiezny (POL) 6-4 6-2
*Lu Yen-Hsun (TPE) bt Igor Sijsling (NED) 7-5 7-6 (7)