Portsmouth boss Steve Cotterill felt his side had got their just rewards after Luke Varney's injury-time equaliser rescued a point at the Riverside Stadium.
Rhys Williams looked to have earned all three points for Middlesbrough when he restored their one-goal advantage nine minutes into the second half, but debutant Varney fired home from close range in the 92nd minute to deny the hosts.
Cotterill Portsmouth's official website, www.portsmouthfc.co.uk: "From about 80 minutes onwards we got into the ascendancy, built up a head of steam and got the equaliser we deserved."
He added: "I think a few people would have had Middlesbrough down for a home win, because they finished the season like a train, so we're very pleased with the result. There are plenty of plusses."
The match was played in difficult conditions, with torrential downpours soaking the playing surface.
"It was an awful day," Cotterill added. "We were so wet at half-time that all the coaches had to change their kit.
"There was a corner of the pitch where it was so wet the players had to literally flick it up and volley it, but despite the rain there was some good football played, although (Boro manager) Tony Mowbray will probably be disappointed with the defending for our two goals, as I was for theirs."
Pompey were only able to name four substitutes, with 17-year-old Ryan Williams - the brother of Middlesbrough goalscorer Rhys - and veterans Kanu and Christian Dailly all being introduced after the break.
"We've just about got a team, putting a 17-year-old on the bench and Christian Dailly, who we signed on Friday," explained Cotterill.
"Otherwise we would have only had a keeper and Kanu as subs. But the subs came on and played their part. Without them we wouldn't have got the result we did."
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