Spurs were beaten 1-0 at home in the north London derby by Arsenal on Sunday, with a goal from Tomas Rosicky inside two minutes proving enough to secure victory for the visitors, who reignited their title bid.
A second successive Barclays Premier League defeat following on from the 4-0 drubbing at Chelsea leaves Tim Sherwood's side fifth, some seven points off Manchester City, who have played three matches less.
It would now be a tall order for Spurs to close such a deficit over their remaining eight league games, which would see a season which had started with such hope following a £100million-plus summer investment under former manager Andre Villas-Boas end in the disappointment of missing out on Europe's elite club competition once again.
"I do not want to look at the table any more because the gap (on the top four) is very big," said Belgian defender Vertonghen.
"All four sides at the top are stronger than they were last year and we have stayed at the same level. If you see last season, then we did not improve.
"(However), I think we do have the players to achieve Champions League (qualification) and I hope we can achieve it next year."
Spurs have little time to reflect on just how they failed to convert the majority of possession into goals against Arsenal - midfielder Nacer Chadli spurning the best opportunity at the start of the second half following a handling error from goalkeeper Wojciech Szczesny - as they have to face the second leg of their Europa League tie away to Benfica on Thursday night, in which they trail 3-1.
Vertonghen admits the Spurs squad must quickly regroup.
"Of course we are all disappointed but we will try to come back with some good results," he said.
"It is difficult now but we have to (pick ourselves up) and go again."
Full-back Danny Rose accepts Spurs must learn to be clinical if they are to make that next step under Sherwood.
"Once the manager took over in December, we were on fire and we have had a bad week where we have become detached from the top four and it is hard to take," he said.
"It is going to be very hard to break in this season. We might have to look to next season now, regroup and see what happens."
Rose added: "Some of the games we have lost at home and drawn at home, it has been unacceptable - Tottenham of two or three seasons ago were beating these teams comfortably.
"It is something to look at and we're definitely disappointed that this season may go again without finishing top four.
"Against Arsenal is the best we have played in a very long time, but the difference between the top four and the teams below is once they get a chance, they take it."