Pompey came up against the only side above them in the League One standings at the weekend.
But a 2-1 victory at Peterborough – courtesy of goals from Oli Hawkins and Jamal Lowe – means it is now the Blues sitting proudly in top spot.
Tom Naylor hailed an impressive all-round performance, which saw goalkeeper Craig MacGillivray well protected.
But the midfielder was slightly frustrated that Pompey could not quite see the game out without conceding.
He said: “The positions don’t really mean much at this stage of the season, but you always want to win and it’s nice to go top.
“It was a good performance and we did what we had to do in order to come away with all three points.
"I thought we did well – particularly the two centre-backs – to keep heading the ball back out."
“We got a bit sloppy towards the end of the game and that resulted in the Peterborough goal, which was disappointing.
“That’s not like us and it’s something for us to learn from because it’s important to be able to shut up shop and protect a lead.
“They’re quite a direct side and were looking to just keep on smashing the ball into our box from set-pieces.
“That’s the way they play and everyone’s different, so you have to get used to facing different styles throughout the season.
“I thought we did well – particularly the two centre-backs – to keep heading the ball back out. They did the job well.
“We weren’t really troubled in the first half and then got the goals from Oli and Jamal after the break. It was pretty comfortable overall.
“The only time it got nervous was right at the end when they scored and we perhaps needed to show a bit more experience.”