Adam Dugdale's second-half header gave Crewe a narrow 1-0 win over Southend in first leg of their npower League Two play-off semi-final.
Following a first half of few chances, Alex centre-back Dugdale headed home Ashley Westwood's 49th-minute free-kick to end the visitors' run of five consecutive clean sheets and send Gresty Road into raptures.
It was no less than Steve Davis' side deserved as they extended their unbeaten run to 17 matches by outplaying a Southend team who recorded a league double over them this season.
Paul Sturrock's men also headed into the game in a rich vein of form, winning four of their last five to miss out on automatic promotion by a point, but turned in a subdued performance.
Michael Timlin, Bilel Mohsni and Ryan Hall all went close as a belated rally arrived from Southend, but they emerged with nothing to take back to Roots Hall for Wednesday night's second leg.
Davis hailed his young side for their composure under pressure.
"It's fantastic thing for the players," he said.
"They'll learn a lot from today having not been in this situation before .
"There's five or six of them that are in their first season in professional football.
"I've enjoyed the fact that we've played exactly how we did on our run. They played with confidence, they've been smiling, they enjoyed the atmosphere - they've soaked all that up.
"That's not easy for young boys to get through. It was a big contest between experience and youth.
"Now we've got to do it all again and that's going to be very hard. They'll be wounded so we've got to be ready for what they throw at us next week."