A Shea Charles wonder goal helped promotion-chasing Saints secure their ninth Championship win in 12 games with a 2-0 victory over Oxford.
Cyle Larin was also on target as Saints extended their unbeaten run to 12 games in the league and consolidated their place in the top six.
With Saints inside the top six on goal difference with seven games to go, Eckert insists the job is far from done and urged calm within his squad.
“I think the mood is very professional. I think it’s been a test of maturity today because those games are not easy to play,” insisted Eckert.
“When you know you have the ball for long spells, you have to then maintain the rhythm of the game. We tried to start strong, obviously.
“There’s never a guarantee that you can open up a game early, but the boys knew there was a chance to start strong. The first 15 minutes were excellent.
“Oxford are a well-managed team, it’s never that easy. They have transition threats up front, and the more players you push up, the more risk you take.
“Then it’s always about the balance, being on the ball and creating some things but not giving up too much in case you do lose the ball in some areas.
“Overall, we are very happy, the atmosphere was good in the dressing room, but not too euphoric, and it shouldn’t be.
“There are a couple of big games coming up now for some of the boys who go to the national teams; the other ones have a couple of days off.
“Then we will come back, and we have to go again.”
Eckert made tactical changes from the teams that faced Coventry and Norwich as Cam Archer, Tom Fellows and Charles were introduced into the starting lineup.
Finn Azaz was deployed on the left but inverted to get on the ball, leaving Ryan Manning to provide width, while Fellows had a more traditional role.
Saints reverted to their usual 4-2-3-1 once Cam Archer was replaced by Sam Edozie in the second half, allowing Azaz to step into a more central role.
“I think it’s always about an idea of how you want to start a game, but also to anticipate how you might want to finish a game,” explained Eckert.
“Then it was a decision to make if Leo Scienza makes it on the matchday squad or not, and then how many wingers we have available on the bench.
“It was a first start for Sam in a long, long time, midweek, and we could have started with him, but then obviously you can’t play for 90 minutes.
“I think it’s then not so easy, because I think against those teams sometimes you need one-on-one players on the sides at the end of these games.
“So we thought it might be a good idea to have Ryan a little bit higher and Azaz inside, to give us the option to finish the game how we did.
“Obviously, the game was at a different state after 60 minutes, but it was an idea just to be prepared for different scenarios of how the game might develop.
“I think Ryan has done that very well, and Sam has done very well when he came on, so I think we did great in both set-ups this afternoon.”