Pompey's perfect league start came to an end as they battled to a 0-0 draw at Doncaster.
That meant the Blues couldn't equal the club's best winning start to a season at the fifth attempt.
Kenny Jackett's men came under intense first-half pressure, but were much better after the break after the introductions of Brett Pitman and Ben Close.
There was drama seven minutes from time as keeper Marko Marosi handled outside his box and was sent off.
With all three Doncaster subs used midfielder Ben Whiteman went between the sticks.
But, aside, from a tame Ronan Curtis effort late on Pompey couldn't test the makeshift keeper.
The first half saw Pompey under incessant pressure from the home side.
Andy Butler headed wide in the fourth minute to set the tone for the opening 45 minutes.
Then Ben Whiteman fired a free-kick not too far over before Jamal Lowe lost the ball to John Marquis in the 12th minute, who played it to Alfie May but his shot on the turn was gathered by Craig MacGillivray.
Pompey fans were fuming with May in the 20th minute as he appeared to go to ground theatrically as Anton Walkes challenged, but the ref played on.
Herbie Kane's 34th-minute cross hit Jack Whatmough and appeared to be on the way in until MacGillivray recovered to gather the ball.
Jackett introduced Pitman and Close at the break for Ben Thompson and Oli Hawkins, as he looked for his side to get a foothold.
Lee Brown produced an important clearance to deny Marquis in the 54th minute.
Gareth Evans had Pompey's best chance three minutes later when Marko Marosi made a point-blank stop to deny him from Ronan Curtis' cross, and could only force the loose ball into the side-netting.
Then Marosi made a double stop to deny Pitman and Evans before Evans' second stab at goal was cleared off the line by Whiteman.
There was drama with eight minutes left as keeper Marosi was sent off for handling outside the box as Curtis pressured.
With all three subs used for Doncaster that meant midfielder Whiteman picked up the gloves.
Pitman whistled the resulting free-kick just over the top with the match set for a grandstand finish.
But there was no way through for Pompey with Curtis firing at Whiteman the only late chance for the visitors.