Joe Rafferty and Jake Forster-Caskey both saw red in the 56th minute following a skirmish in the goalless Lamex Stadium draw.
It was the main talking point in a tight affair with few goal-scoring opportunities between either side in which the benches repeatedly clashed.
Although referee Simon Mather became the third official in three successive matches to be forced off through injury, coming off in the 86th minute to be replace by his fourth official.
Still, it represented an afternoon of frustration for John Mousinho’s men, who created little while registering a fourth successive League One clean sheet.
By doing so they have now gone 16 league matches unbeaten, stretching back to last season, thereby representing a club record.
However, a third draw in their opening five matches needs addressing if they are to push for promotion.
Mousinho had made two changes for the trip to Stevenage, with Jack Sparkes and Abu Kamara named in the starting XI
They replaced Anthony Scully, who wasn’t in the match-day 18, and Alex Robertson, who dropped to the bench.
Sparkes and Kamara both lined-up for Pompey in their EFL Trophy clash with Fulham Under-21s on Tuesday night.
While for the former Exeter man, who operated on the left wing against Boro, it represented a full league debut for the Blues.
In a slow start to the game, both skipper Carl Piergianni and goalkeeper Tay Ashby-Hammond had to receive on-pitch treatment for the hosts in the opening 13 minutes.
That disrupted the tempo of the encounter as the match struggled to get going amid sporadic rain and sunshine.
On 20 minutes, Alex MacDonald’s throw from the right was flicked on by Aaron Pressley and found its way to Jamie Reid at the far post.
His header appeared to be sneaking in, but Will Norris produced a magnificent flying stop to tip the ball around the post and prevent a certain goal.
At the other end, Joe Rafferty’s from the left presented Regan Poole with a great headed opportunity at the far post, but he planted it well over the bar.
Pompey were growing into the match and provided a decent threat down the right, with testing shots from Joe Morrell and then Kamara blocked by home defence.
On 38 minutes, another throw from MacDonald resulted in Jordan Roberts striking the right-hand post, much to the Blues’ relief.
With no changes at the interval, Connor Ogilvie was called upon to head the ball off the line after Rafferty had partially deflected a cross, looping up invitingly.
Rafferty and Jake Forster-Caskey were both dismissed in the 56th minute after a scuffle between the pair.
Having gone into a tackle together, the duo tangled on the floor, with the Stevenage man appearing to throw a punch and was the first to be sent off.
He was then joined by Pompey’s right-back, after being alerted to the incident by the fourth official, and it was 10 versus 10.
There was further drama when Mather took a tumble and had to be replaced on 86 minutes by fourth official Stephen Finch.
Still, the match remained goalless as the Blues made it 16 league matches unbeaten.