Manager Carl Fletcher admitted his disappointment as Plymouth drew 1-1 with Paul Sturrock's Southend.
On-loan Burnley forward Alex MacDonald fired Argyle ahead in the 50th minute, shooting under Daniel Bentley after latching on to Guy Madjo's cross from the right.
United levelled through Watford loanee Britt Assombalonga five minutes later, as the striker spun his marker and then drilled the ball under Argyle goalkeeper Jake Cole.
Fletcher admitted: "We are disappointed we did not get three points. We played well in the first half and little bits of the second half.
"We just feel it's a little bit of an opportunity missed but Southend will be there or thereabouts at the end of the season. They have had four wins in the last five games, so we knew it would be a really tough test for us.
"Once they brought Ryan Leonard on, with his long throw-ins, then we had to cope well in the air because they have got some big players.
"We played really well. I was really pleased we scored so soon after half-time it was just a little bit of a disappointment we could not kick on from there, but we are not too disappointed."
Sturrock bemoaned his side's display, saying: "I was very disappointed with our first-half performance. We looked lacklustre and a bit sloppy even though we had a couple of decent chances that we could have done better with.
"I thought Plymouth shaded the first half and we came out and were sloppy again in the first 10 minutes of the second half.
"But then we started to ground things down, made our substitutions, got out goal and I did believe that we were going on to win that game."