Henman has been runner-up three times at Queen's Club

Henman, 31, overcame former Wimbledon champion Agassi 6-4 6-4 in the pair's first meeting on grass.

In baking conditions at Queen's Club, the pair traded early breaks before Henman moved ahead at 4-3.

After taking the first set, Henman then broke the American in the first game of the second before wrapping up the win.

Highlights: Henman beats Agassi at Queen's

But fellow Briton Martin Lee was soundly beaten 6-3 6-2 by Spaniard Fernando Vicente, while Scottish teenager Andy Murray looks set to start his campaign against Serb Janko Tipsarevic on Tuesday.

I've been serving pretty good and that bodes well - it's a good sign Tim Henman

But it was Henman who was first to kickstart his grass-court season with a promising win against eight-time Grand Slam winner Agassi.

The American was seeded 12th on his return to competition after more than two months out.

The 36-year-old opted to miss the entire clay-court season in order to rest his troublesome back and get the best out of the grass-court season.

But he was outclassed by Henman, who has also struggled with back problems during a slump to 76th in the world and third in Britain.

"I've been serving pretty good and that bodes well - it's a good sign," said three-times finalist Henman, who landed seven aces during the match.

"I'm feeling pretty good physically - I've had a minor blip but feel like I've managed it well.

"It's just making the transition from clay to grass - you're waiting for the ball and sometimes it's dropping a lot.

"The extra bending put a bit of stress on my back but I didn't feel too restricted and served extremely well when I needed to."

Other Britons in action this week are wildcards Alex Bogdanovic and Jamie Baker.

Baker will meet Surbiton Trophy winner Mardy Fish on Tuesday with a second-round clash with French Open champion Rafael Nadal the prize, and Bogdanovic faces Russia's Dmitry Tursunov.

Nadal, defending champion Andy Roddick and Lleyton Hewitt have all been given first-round byes.