The summer signing was a half-time introduction in Latics’ FA Trophy third round tie at home to Mickleover and scored with one of his first touches to make it 2-1.
The game was settled by a penalty shoot-out after ending 3-3, with Willoughby confidently dispatching from 12 yards to set Oldham on their way to clinching it 4-2 on spot kicks, thanks to two saves from goalkeeper Mat Hudson.
And the former Chester striker is looking to take confidence from getting off the mark.
“It’s exactly what I aim to do when I come on, I wanted to make an impact,” said Willoughby.
“I made a run in behind, Charlie (Raglan) played a good ball over the top and I got the defender one-v-one and I thought ‘I’m going to shift it past him and shoot across goal’ and luckily it went in at the back post.
“I found a bit of space and I knew I could shift it and get my shot off and just get it across the keeper, and that’s what I did and it went in.
“It’s something that I practice quite a bit so it was good that it came off.
“The manager just wanted to change it up a little bit. Devarn (Green) got injured in the first half so he just wanted me to get on the pitch and do what I can.”
It has been a patient four-month wait for a goal for Willoughby, whose reputation as a sharp-shooter was one of the reasons Latics launched a relentless pursuit for his signature under former boss David Unsworth.
The 26-year-old has not been utilised as much as he would have envisaged, making just four starts in the league, which has contributed to his goalless streak.
“It hasn’t gone as I thought it would but obviously I’ve got to keep my head down, keep training hard, take the opportunities when they come and hopefully I can stay in the team and get the goals,” he said.
“I just try my best every time I play.
“I’ve been waiting a while (to score). It’s been a long time and I’ve been dying to score whenever I’ve had the chance to be on the pitch. Whether it be a league or a cup game I’m over the moon to get off the mark.
“Each game that goes by it’s been getting more frustrating but it’s something that I’ve got off my back now and hopefully I can kick on now and get some more.
“It gives me confidence in myself as well. Scoring’s what I love doing especially if it helps the team win, so hopefully it continues and I can take it into the next games.”