NEWCASTLE, England — Mauricio Pochettino apologised to Tottenham Hotspur fans after Sunday’s 5-1 defeat to relegated Newcastle and called it his “worst day as a manager.”

More than 3,000 Spurs fans made the 570-mile round trip to St. James’ Park, with their team needing a point to guarantee second place and a first finish above local rivals Arsenal since the 1994-95 season.

But Spurs were humiliated by a Newcastle side reduced to 10 men in the second half and slipped to third after Arsenal’s 4-0 win over Aston Villa.

The visitors trailed 2-0 at half-time but had hope when Erik Lamela halved the deficit before Aleksandar Mitrovic was shown a straight red card for a bad tackle on Kyle Walker.

However, they slumped to their heaviest defeat under Pochettino, and the Argentine told his postmatch news conference: “First of all, I would like to apologise to our fans, our team was terrible for them.

“It’s my worst day as a manager. Not just in England — in Spain, too.”

Pochettino previously said he did “not care” about finishing above Arsenal, explaining that he wants to finish above every team and urging Spurs to focus on themselves.

But he said it hurt to have slip below their neighbours at the final hurdle, having been ahead of the Gunners in the table since January.

“It’s very bad — I feel bad because the worst is that on the pitch we showed we don’t care about the position in the table. This upset me and disappointed me,” Pochettino said.

“It’s important to analyse the goals, the formation of the squad and make some decisions. In our head, yes, we wanted to be second. Of course.”

Since squandering a lead to draw 1-1 with West Bromwich Albion on April 25 — a result that all but ended their hopes of catching eventual champions Leicester — Spurs have taken one point from a possible nine.

On Friday, Pochettino said his young squad must improve their “mental state” to be “more strong” next season and he reiterated this message.

“I don’t think it was a tactical problem or about physical conditioning. What we have said the whole season and the last few weeks is that we need to improve our mentaility, he said.

“Today we can see the problem from the beginning was that we were not ready to compete. Today we weren’t the team we showed the whole season.

“We need to have clear ideas about the future and how to improve and, if we want to fight for the big things, we need to avoid performances like today.”