Pochettino's men host AEL in the second leg of their UEFA Europa League play-off on Thursday and hold a 2-1 advantage after late goals from Roberto Soldado and Harry Kane in Cyprus last week.
With Spurs to host Thursday's clash, they are heavy favourites to progress to the group stages of Europe's second-tier competition.
But Pochettino is wary of an upset and said Milton Keynes Dons' shock 4-0 League Cup win over Manchester United on Tuesday has him cautious.
The third-tier English side thrashed United and Pochettino said the result serves as a good example for his team, who have taken six points from their first two Premier League games of the season.
"I think it is a different game than what we played in Larnaca against Limassol," Pochettino said.
"We need to be focused and ready. I believe that it will be a tough game because all games are difficult.
"Now we need a very good performance to beat Limassol and because we need to stay in the next round.
"On Tuesday it was difficult for Manchester United and you need to be focused on your objective.
"I watched the game in Milton Keynes live. I was there. It was difficult but it's a good example to be ready.
"We got a good result in Larnaca but we need to ready and focused on the game."