Lance Armstrong found the opening stage of the three-day Tour of Ireland tough going on Friday, finishing 16 seconds behind stage winner Russell Downing.

"It was a tough start for me. I don't know about everyone else," seven-time Tour de France winner Armstrong told reporters after finishing 23rd.

"It all takes it out of you. The combination of the up and down terrain, the rough surface, the twisty turny roads, the wind and then a lot of accelerations. You know you've raced at the end of it."

American Armstrong, who last raced in Ireland in 1992 in his first year as a professional, said he did not expect to challenge for overall victory.

"We'll see what happens. I haven't been doing a lot of specific road work but hopefully I'll feel better as the days go on," he said.

"It'll all comes down to the last day. Somebody will probably make a separation, but probably not me."

Saturday's 196-kilometer second stage is from Clonmel to Killarney. The Tour of Ireland ends in Cork on Sunday.