Scott Lindsey was in no mood for celebration despite his Crawley side taking a firm grip of their Sky Bet League Two play-off semi-final by beating MK Dons 3-0 at the Broadfield Stadium.
The Red Devils go into the return leg at Stadium MK on Saturday with a sizeable advantage after first-half goals from Liam Kelly and Jay Williams put them in charge before a sell out crowd of 5,564.
Substitute Ronan Darcy struck with a deflected shot after 65 minutes to leave boss Lindsey pleased but warning that the job was far from done.
The former Swindon manager said: “We’ve given ourselves a good chance but it will be tough on Saturday and it’s only half-time.
“We need to be professional and humble – it’s not done yet.
“I am not celebrating and I have told the players not to celebrate.
“We knew it would be a tactical game. We are in a good position but we still have lots to do.”
This was only the fifth clean sheet Crawley have kept at home since the start of the season and Lindsey added: “We defended well all night and we got it right tonight.”
MK Dons boss Mike Williamson admitted that the result had left his men with “a mountain to climb” in Saturday’s return leg.
The Dons will have it all to do having never gained promotion via the play-offs in five previous attempts.
Williamson said: “We never looked anything like us.
“We could have scored early on but then Crawley scored. Now we have to dust ourselves down and keep our heads.
“I thought in the first half we didn’t pick up on second balls but improved afterwards.
“I’ll never criticise us for missing chances as we are getting in those positions.
“We wanted to score a goal and now we must make sure the mindset is right on Saturday.
“All goals are avoidable and now we have got a mountain to climb.”