“But then I believed in myself in the third and trusted that I could get it done if I just gave myself another opportunity,” he said.
Harrison said he already received congratulations from older brother Ryan Harrison, who also is in this week’s field, as well as TV analyst Justin Gimelstob.
Christian said Ryan kidded him during the Newport, R.I., tournament two weeks ago, asking Christian if he was going to win an ATP match before Ryan won an ATP tournament.
“It was good that I could get it soon after that,” Christian said.
He will face John Isner, the tournament’s top seed, Thursday in the second round.
Other matches Wednesday: Mardy Fish's comeback on the ATP Tour stalled with a 6-4, 2-6, 5-7 loss to Michael Russell in the first round.
Fish, twice a champion at the Atlanta Open in 2010 and ’11, was competing in his second ATP World Tour event this year and first event since Indian Wells in March. He experienced an abnormal heart condition in 2012 that sidelined him after the U.S. Open and then again after Indian Wells. He played a Challenger Tour event in April.
Fish went ahead 2-0 in the third set before Russell rallied to win four of the next five games. Russell appeared ready to break Hewitt in the eighth game before Fish bounced back to tie the set at 4-4. Russell took a 6-5 lead and then broke Fish to win the match.
In an earlier match, Lleyton Hewitt knocked off Rhyne Williams 7-6 (6), 6-4 to advance to the quarterfinals.
Williams, who played at Tennessee for two years before turning pro in 2011, was ahead 6-2 in the tiebreaker of the first set before Hewitt rallied.
Hewitt, who won the U.S. Open in 2001 and Wimbledon in 2002, will face third-seeded Ivan Dodig, who defeated Ricardas Berankis 6-1, 6-7 (3), 6-3.
James Blake beat Tim Smyczek 7-6 (3), 4-6, 7-6 (4) to advance to the second round. He will face Evgeny Donskoy in the second round.
Matthew Ebden advanced after Ivo Karlovic withdrew citing fatigue. Ebden was leading 6-2. Ebden will play Kevin Anderson, the second seed, in the second round.
In doubles, Rajeev Ram and Ken Skupski defeated Dominic Inglot and Frank Moser 6-4, 6-4.
Memoriam: Atlanta Open officials are wearing a patch with the initials "BD" on their shirts this week to honor Brad Drewett, a former player who eventually became the ATP president in January 2012. He died in May at the age of 54 because of complications related to Lou Gehrig's disease.