At 8-under-par, Poulter leads by one shot over Australias Peter Lonard (65), and by two over Irelands Paul McGinley (66), while Adam Scott and Padraig Harrington sit three off the pace following opening-round 67s.
For Poulter ' this years Moroccan Open champion ' his score marks the lowest of his young career on the European Tour.
Ive felt pretty happy with my game, and as Ive progressed over the last couple of years, its been a gradual process of getting my swing more on line, he claimed after his round.
Every week its getting closer and closer.
Serving as defending champion at last weeks Italian Open, Poulter was quite close then as well, finishing in a tie for third, and in just his second full year on tour, he is turning heads in big ways.
Its been a long year for me, just missing out on the Ryder Cup, he claimed of his narrow miss at the biennial event. Ive played a lot of tournaments and some weeks Ive been playing while tired, but Ive now had a lot of rest and come back and played pretty well.
With six birdies, an eagle and no bogies on his card Thursday, it would seem that he is indeed playing well.
One shot behind, however, a hungry Lonard is still searching for his first title on the European circuit, after recent injuries to his eyes and wrists.
I broke my wrist last summer and was out for 12 weeks, Lonard said. It worked out all right because I got laser treatment for my eyes while the wrist break mended. This is probably the first year since 1992 that Ive played a full year without any interruptions.
McGinley seemed to be playing without interruption on Day 1, as the Irishman eagled the 16th and closed with a birdie at No. 18 for a fine 66. Like Poulter, he is searching for his second win of the year.
Harrington, however, is attempting to win just his first.
With seven runner-up finishes this year alone, the 30-year-old might be the sentimental favorite this week, yet he continues to grind.
I am very pleased to finish 5-under because I dont think my hands and arms knew what my body was doing today, said Harrington.
I hit a lot of good shots and plenty of bad ones. However, its a very important week and it wasnt time to get down on myself.
Full-Field Scores from the Volvo Masters Andalucia.