Mark Winterbottom and stand-in engineer Campbell Little endured a rough reunion on Saturday at Sydney Motorsport Park.
The highly experienced Little had been a last-minute call-up to replace Winterbottom's regular race engineer Grant McPherson, who is suffering from glandular fever.
Winterbottom took 11th and 12th place finishes from the two races after starting each 100km encounter mired down in 17th.
The results see Jamie Whincup's championship lead over Winterbottom grow from 15 to 69 points.
“It was a pretty disappointing day really, the car just isn't there, we're just not quick enough,” explained Winterbottom, whose team-mate Chaz Mostert managed second in Race 27.
“We tried to salvage something, Chaz looked like he did a good job, so it was nice to see him quick, but my car is just nowhere near it at the moment, so we need to tune it up and come again tomorrow and keep trying.
“It's really frustrating when you're in the pack, and it was pretty scary out there (in the wet).”
Winterbottom and Little worked together for three seasons from 2010, while the latter remained at FPR on its fourth entry for the balance of last year.
Having then worked at FPR customer squad Dick Johnson Racing until last month, Little admitted to needing to catch-up on the factory outfit's progress.
“It was a bit of a struggle,” Little told Speedcafe.com of the day.
“We didn't really have it in the dry or the wet, so we've got to work away at it.
“It seems to be on a knife-edge, it's either good or it's not, and we've only got one of those two at the moment.
“There's a bit of learning (for me) as well because things have changed in six months or so.
“At DJR we went down one road with Scott (Pye) and he seemed to like it, but here Mark has gotten into a happy place where his car was a reasonable race car but hasn't quite got it sorted for qualifying.
“All of that just hasn't added up to starting off with a good car here.”
McPherson played a reduced role in the engineering of the #5 Ford throughout the day, but will be absent entirely tomorrow due to his poor health.
“We were sticking to their (Winterbottom and McPherson's) methods and the areas that they've played in today,” added Little.
“We'll have a discussion about it tonight and see if they want to try something different tomorrow.
“We had a bit of a go in the second race but we'll have to go back and look tonight at how it was.”