Tottenham Hotspur head coach Mauricio Pochettino urged his players to improve after they again failed to convince in defence in a 2-1 Europa League win at Asteras Tripolis.
Spurs moved to within a win of the Europa League knockout stages after condemning the Greeks to their first-ever home defeat in continental competition.
The north Londoners were two goals up at the break thanks to an Andros Townsend penalty and a header from Harry Kane, but a shaky performance in the second period saw Asteras notch up 14 efforts on goal.
The hosts scored late on when Jeronimo Barrales converted a penalty given for a foul that saw Federico Fazio sent off, but Spurs held on.
"I think that during the first half we were better than Asteras,'' Pochettino said. "We played well during some moments and scored two goals.
"After half-time, they started well and created one chance very early. They created some chances and at the end, with the Fazio penalty and him being sent off, it made it difficult.
"We need to improve, we need to work, we need to realise that we need to improve in different aspects of the game.
"I think that we played very well, but the second half was different and we need to review the game and improve."
Tottenham's awkward second half mirrored the uncertain recent performances that led England coach Gary Neville to say they are "weak" mentally.
Spurs unravelled after half-time against Newcastle at White Hart Lane, where the visitors transformed the game by scoring seconds into the second period, and needed two late goals to salvage anything from their game at Aston Villa.
But Pochettino defended his players, saying: "If you have a weak mentality, it would be there in 90 minutes, not only in some moments in the game.
"I explained after the game with Newcastle that we need to work very hard with our mentality to be focused on the game for 95 minutes.
"It is one aspect that we need to improve -- but it is a difficult aspect to improve in football."