Manager Carl Fletcher admitted his disappointment as Plymouth drew 1-1 with Paul Sturrock's Southend at Home Park.
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.
"We played some good stuff, we have been working on it all week, trying to get men in pockets and I thought Onismor Bhasera did it really well. We also worked on getting our strikers down the channels and Warren Feeney and Guy Madjo did really well, and worked tirelessly."