Jessica Simpson's ex-boyfriend Tony Romo is said to be emotionally drained from the couple's split.
The football player battled lapses in concentration at the American Century Celebrity Golf Championship this weekend because he was distracted by his recent break-up.
Tony said: "The more stuff you've got in your mind, probably the less successful you're going to be."
"So, the only thing I think about is the task at hand. When you let your mind wander or think about other things, you're setting yourself up for failure. I just try to stay focused."
Tony parted ways with Jessica just before her birthday on July 10, prompting female fans to line the 17th and 18th holes of the tournament - held in Lake Tahoe on the border of Nevada and California at the weekend - waving handmade signs of support.
One fan even yelled, "We don't like that Barbie either," but Tony showed no reaction and later finished the tournament in second place.
Meanwhile, it has been alleged Tony spent the night of Jessica's birthday with "Blame It on Rio" actress Michelle Johnson.
Gossip website X17online claims to have obtained pictures of Michelle, 43, at the 29-year-old athlete's hotel the following day.
Jessica, 29, was spotted on a girls' night out on Saturday in a bid to forget about Tony.
Meanwhile, Jessica's mother Tina Simpson has quashed rumors her daughter is to reunite with ex-husband Nick Lachey. Replying to a reconciliation question on her Twitter blog, Tina wrote: "NOT happening! Great man just not in the cards!"
Jessica and Nick were married from 2003 to 2006 and starred in MTV reality show, "Newlyweds."