Roberts, who leads the Champions Tour in scoring average, had his low round of the year, 7-under-par 64 on Friday, to take a one-stroke lead over Romero after the first round of the Commerce Bank Championship.
Roberts' only tour win this year saw Romero finish second, and the two met in a playoff in last year's Senior British Open with Roberts winning that, too.
Roberts made the turn at 2 under, but he had five birdies over his final eight holes. Roberts, who is tied for the tour lead in putting average at 1.706, needed only 29 putts and hit all but one green in regulation.
Romero was strong with his irons, as the longest of his six birdie putts was from 7 feet.
PEEK'N PEAK CLASSIC: In Findley Lake, N.Y., Paul Claxton shot a second-consecutive 6-under-par 66 to open a four-stroke lead in the Nationwide Tour event.
Aiken's Brian Quackenbush shot 71 and is tied for ninth at 139.
Former Thomson resident Franklin Langham shot 73 and is tied for 17th at 140.
Augusta's Scott Parel shot 75-74-149 and missed the cut by six shots.
FRENCH OPEN: In Versailles, France, Simon Khan shot 4-under-par 67 to take a one-stroke lead over Paul McGinley and Colin Montgomerie after the second round of the European Tour event.