There were four Fratton debutants on the pitch when the second half kicked off.
Stuart O’Keefe and Oliver Hawkins were joined by substitutes Matty Kennedy and Nathan Thompson, as Pompey tried to rescue something against Rotherham.
Ultimately they were unsuccessful, with Jon Taylor’s fierce strike enough to secure all three points for the Millers.
That was despite a vastly improved performance after the interval, with plenty of chances created and strong cries for a penalty turned down.
And Kenny Jackett was disappointed that Pompey could not find the leveller that their second half dominance perhaps warranted.
The Blues boss said: “Hawkins looked a useful acquisition for us and was a decent threat in the box. It was a shame that he had to come off.
“O’Keefe came into the game and got a lot more second balls, while Thompson shored things up for us because Taylor had been a threat.
"In a very battling game we missed key opportunities and didn’t get a decision."
“Kennedy is a good deliverer of the ball with his right and left foot, so we have to work them all in to create an effective team.
“It was also good to have Matt Clarke back and he played well – there were no after effects from his injury.
“We came back into the match in the second half and dominated, but obviously couldn’t find a goal.
“There were two big chances for us either side of the break from Jamal Lowe and we had a decent penalty appeal turned out.
“But in a very battling game we missed key opportunities and didn’t get a decision – that’s how close it was.
“We’ve had close matches so far, but we want to improve and become a winning force in this division.”
Jackett brought off Conor Chaplin and Jack Whatmough at half-time, switching from a new 3-4-1-2 system to a more familiar one with four at the back.
He said: “We needed to put more emphasis on our forward play and our work out wide in particular.
“Rotherham sat deep and we knew that would happen, so we needed to have enough bodies in wider positions. But their centre-backs handled what was thrown at them pretty well.
“The changes we made were more tactical than an assessment of their performances in the first half.”