The First Division's in-form teams cancelled each other out in a tense goalless draw at the Madejski Stadium.
With Reading coming into the game in search of a seventh straight victory and Portsmouth for their fifth win on the bounce, a draw was perhaps the most likely outcome but Reading would have been more disappointed not to have taken all three points.
They created the better chances and were still searching for victory long after the league leaders had apparently settled for a point.
In striker Nicky Forster, Reading boasted the first division player of the month and the best player on the pitch.
The former England Under-21 star had Reading's best chances, the first after 25 minutes of action, when he flicked a clever left-foot shot just wide with Pompey keeper Shaka Hislop rooted to his line.
But Forster should have done better a minute later when he finally got the better of his determined marker, Hayden Foxe, and wriggled into the box.
But with a pass to the unmarked Andy Hughes the better option, Forster instead opted to shoot from a tight angle and blazed badly over the crossbar.
Pompey, seven points clear at the top coming into this game, created few chances and playmaker Paul Merson seemed to stroll through the game.
Reading though finished the first half strongly and should have gone into the break in front.
First Hislop pushed away Forster's low cross then repositioned himself well to gather John Salako's follow-up.
Hislop did even better in first-half stoppage time when he blocked bravely at the feet of Salako and Pompey were relieved to see the offside flag raised as Forster slammed the rebound against the inside of a post.
After another second-half stand-off, both sides had chances for a late winner but, true to the form of the game, both ended up with messy finishes.
Forster had a fine chance to finally break through two minutes from time when he ran on to a pass from substitute Kevin Watson, but again shot over the bar from just inside the box.
But Svetoslav Todorov was even more red-faced at the other end when he wriggled his way into space, but fell over the ball as he sent a shot sideways from the edge of the Reading box.
That allowed Reading to boast a seventh successive clean sheet and Pompey boss Harry Redknapp admitted he was happy with a draw, saying: "We always go out looking for the win but if I'm being honest I would have settled for a point beforehand.
"Reading are a very good side and are on a terrific run of form. A point away from home is always good but especially so in a game like this."