Chris DiMarco refused to get carried away despite moving into a one-stroke lead on day one of the Masters.
The 36-year-old moved to four under par after 14 holes before the rain-delayed day was brought to a close.
DiMarco said: "I've felt comfortable every year I've been here. But this is just the start of the race.
"This is a marathon and we have a long way to go. I'm going to have to play 22 holes tomorrow and who knows what can happen out here?"
DiMarco is one shot ahead of Australia's Mark Hensby, who holds the clubhouse lead after completing a round of 69.
The 33-year-old equally downplayed his early efforts.
He said: "Do I have the game to win it? I don't know. But you keep on trying, you don't give up the dream.
"I played really well today, hit a lot of greens and putted really well. Obviously I'm really enthused with the way I played."