It was a second goal in four games for the talented midfielder, who has been drafted into the England under-20 squad for the international against Portugal next week.
But for Jacko, 19, it has been a season of frustration, blighted by injury that has come good just as it is about to end. After initially wishing the season away while recovering from tendonitis in both knees, he now rues the lack of games available to him in this campaign.
"I've had five or six games and I'm feeling decent at the moment," reported Johnnie.
"There's only another three reserve games and I miss next week's one as I'm going away with England. That means I've only got two reserve games left to play.
"A few months ago I would have just said to get this season out of the way, but now I've started playing again it's looking okay. So maybe I've going to have to just have a break and come back and try and play a full season next time."
Jacko's cracker against Chelsea was, in the eyes of many observers, the reserve team 'Goal of the Season'. He picked the ball up on the right of the area, embarked on a mazy little run and unleashed a left-footer that flew into the top corner.
"I got a little bit lucky with the dribble bit, but I got to the edge of the box and, at 2-1 down, I thought 'I might as well have a little crack here' and it flew in.
"I think we played a lot better in the second half, we didn't really get it together in the first.
"We changed the system at half-time and went to a back three rather than a four. I think we passed it a bit better and had more chances, but they still had chances.
"In the end I don't know if we deserved it, but it wasn't a shock to get the goals because we were putting them under pressure."
Jacko has been in the first team squad for the games with Middlesbrough and Leeds, just reward for his perseverance in a difficult season.
"That was good for me as well. I went up to Middlesbrough and then Leeds at home. It's nice to get rewarded for playing quite well for the reserves.
"The boss has been looking at the reserve games and must have been thinking I'm doing okay - maybe the goal will keep me in there for Arsenal!"
Since his return it is a new slimline Jacko that has been taking the field. Never a slender player before his injury, he has made a concerted effort to trim down in order to make himself more mobile and rely less on power.
"I have yeah. When I was injured I put on quite a bit of weight. I was doing a lot of weight training and you're not doing any fitness work because you can't run.
"I put on a bit, but since I've been back I've lost a bit. I was carrying a bit too much at one stage. I still feel I could be a bit slimmer and become more mobile.
"I've definitely made a conscious effort and I've found it does help me get around the pitch. I feel quite fit actually, considering I was out for quite a long time."
By Richard Hubbard
Johnnie Jackson is hoping that his stunning late leveller for the reserves against Chelsea on Tuesday will keep him in the first team squad for the short trip to N5 on Saturday.