Dimitar Berbatov and Robbie Keane, who now have 36 goals between them this season, struck in the first half at the Strahov Stadium to provide a cushion for Juande Ramos’ side as they prepare for the Carling Cup final.

In sub-zero temperatures in the Czech Republic capital, Spurs were cruising until Cerny dropped the ball under his crossbar and David Strihavka finished.

Spurs will face PSV Eindhoven or Helsingborg if they defend their lead in the second leg of the tie next week, although their eyes may be on Wembley the following Sunday if they are not already.

Ledley King was on the bench in Prague but his knee was not risked in the freezing conditions for fear of missing the showpiece against Chelsea.

Once a lead was established, Spurs did not want to risk adding to their injury list which already has Michael Dawson and Kevin-Prince Boateng on it, both with hamstring complaints.

But for Cerny’s error, the plan would have worked perfectly.

If King’s role as a substitute reflected Ramos protecting his skipper, Berbatov requiring treatment on his ankle in the first half would have struck fear into the Spaniard. Berbatov was fine to continue, though, after his treatment.

Losing Jermaine Jenas to injury would arguably be just as damaging to Spurs given his recent form that has earned a recall to the England squad.

Jenas set up both first-half goals, the opener coming in the fourth minute after a typical surging run.

He was stopped on the edge of the area but Berbatov pounced on the loose ball and his low volley caught goalkeeper Martin Vaniak poorly positioned. It was the Bulgaria striker’s 16th of the season and his third in as many Spurs games.

The Czechs, who are top of their domestic league but have not played for two months due to their winter break, almost replied immediately.

Daniel Pudil and Jaroslav Cerny had efforts on goal but neither tested Spurs stopper Cerny, and the hosts appeared to be rusty without a rhythm of games behind them.

The visitors grabbed their second on the half-hour mark when Keane struck his 20th of the season.

Spurs worked the ball out of defence with Jenas again making the yards. His ball split the Slavia defence and Keane finished calmly past Vaniak, who got his angles wrong.

David Hubacek was cautioned for protesting, then Teemu Tainio joined him in the book for a challenge on Pudil.

Tainio was playing at right-back, with Pascal Chimbonda on the left and Didier Zokora in central defence – meaning three of Spurs’ four defenders were playing out of position.

It mattered little at first though as it looked like Spurs would add to the scoring, even if they were not playing at full tilt.

Berbatov forced Vaniak into a double save just before the break when he almost finished off a flowing move with flicks from Keane and Aaron Lennon confusing the hosts.

Tom Huddlestone also forced a full-stretch save from the Slavia goalkeeper, who was atoning for his part in Spurs’ goals.

Huddlestone beat Vaniak early in the second period after weaving through the Slavia defence – but his finish smashed off the woodwork.

Slavia defender Mickael Tavares did have a glimpse of goal but headed over when he met a free-kick. Up to that point it was a quiet night for Spurs goalkeeper Cerny, who was given a warm reception by home fans on his return.

Spurs fans also asked him to salute them, normally a request for Paul Robinson, reflecting how he has cemented his place in the team in the last month. But his night changed with 21 minutes remaining when he failed to deal with Hubacek’s hanging cross. Strihavka, who challenged him, prodded the ball over the line.

Erich Brabec could have levelled but hit the bar from a corner with five minutes left, with Cerny left stranded.