A goal in each half from Josh Onomah and Kazaiah Sterling provide that platform for the return leg on Wednesday, March 18.
There was little between the teams in this first leg but defensively we were magnificent against a team that had scored 17 goals in their previous four ties.
At the other end, Onomah pulled the strings for us centrally with Shayon Harrison and Ismail Azzaoui willing runners throughout and Kyle Walker-Peters a constant outlet down the right.
Chances were evenly spread between the teams and the difference was that we took two clinically - Onomah latching onto a loose ball in the 41st minute before Harrison turned provider for substitute Sterling, who calmly rolled into the corner one-on-one seven minutes from time.
We edged an at times cagey affair in the first half and had the better of the chances and territorial advantage as both teams looked for the opening goal.
After a bright start, our first chance arrived on two minutes when Charlie Owens found Harrison in the box but Bradley Collins was out in a flash to block his effort with his legs.
Chelsea's first sight of goal saw Kyle Scott blast over on 11 minutes and after somewhat of a chess match, it took until the 28th minute for next chance of note as Dominic Solanke cut in from the left but dragged his shot wide.
There were plenty of meaty challenges as you'd expect with so much at stake and the pace of game didn't let up. Owens had a half-chance on the half-hour but scuffed his shot somewhat before Ola Aina fizzed in a cross that asked too much of Tammy Abraham in front of goal.
A precision pass from Azzaoui sent Walker-Peters away on 38 minutes but his cut back evaded Zenon Stylianides and Harrison.
The opener arrived in 41 minutes and owed much to Onomah's persistence. He initially looked for a one-two with Harrison, was crowded out but Fikayo Tomori's attempted clearance deflected back into his path and he needed no second invitation, one touch and the ball was dispatched past Collins and home.
Chelsea went close within seconds of the restart as Anton Walkes' clearance from Scott's cross hit Solanke and flew just wide and the visitors had their best spell just before the hour.
Dasilva fired over from the edge of the box, Solanka then teed up brown, whose shot didn't trouble Tom Glover, Abraham should really have done better from Dasilva's cross and then the best chance as Brown cut back for Solanke, who fired low at goal from eight yards but Glover managed to keep the ball out.
Sterling replaced Owens and slotted in up front with Harrison pushing out to the right.
Chelsea continued to enjoy the lion's share of possession during this spell but we had the chance to break on 72 minutes, Onomah lifted the ball over the back line for Sterling, who was halted by Tomori, penalty appeals waved away.
Glover had to be alert again on 80 minutes as Dasilva broke down the left, his cross came back to him and he lashed low at the near post where the goalkeeper blocked with his legs.
Walker-Peters got back down the right two minutes later and Aina made a vital clearance with Sterling and Walkes ready to pounce.
The second goal arrived just seconds later. Walkes won possession centrally and found Harrison who timed his pass to Sterling to perfection. Sterling took the ball in his stride and finished low across Collins.
Stylianides' free-kick was then sliced just wide of his own goal by Colkett and substitute Jeremie Boga darted into the box as we ticked into added time but Carter-Vickers made the block.
Spurs: Glover; Walker-Peters, Carter-Vickers, Maghoma, Walkes; Amos, Owens (Sterling, 58); Stylianides, Onomah, Azzaoui (Edwards, 75); Harrison. Unused subs: Whiteman (GK), Muscatt, Daly.
Chelsea: Collins; Aina, Tomori, Colkett, Dasilva; Sammut, Musonda, Scott (Palmer, 56); Abraham, Solanke, Brown (Boga, 65). Unused subs: Thompson (GK), Grant, Ali.