We just did not play well enough – Southgate was frustrated by the defeat in England

Gareth Southgate is considering a return to three-man defense, with which England reached the semi-finals of the World Cup last summer.

The three lions meet Bulgaria in qualifying for Euro 2020 on Monday to return to victory following a 2-1 defeat by the Czech Republic on Friday.

Defensive errors were punished in their first defeat in Euro qualifying since 2009.

"It's certainly something we've been thinking about," Southgate said of a possible defensive change.

"I think we are in a difficult position regarding the players who have played international football with us in this part of the field and who regularly play with their clubs.

"That's one reason why we did not do that [against the Czech Republic],

"I am not sure if this is the right thing before Monday, but we are very aware of and appreciate these things."

Harry Maguire, John Stones and Kyle Walker formed the Defensive Three in Russia last summer.

However, Stones is unavailable due to injuries while Walker was not included in the squad.

Asked whether there's still plenty of time left for a defensive change to the system before Euro 2020, Southgate said, "I think so, I think the players are picking up on tactical concepts very quickly, especially the top players.

"So we have to keep thinking about what works, what is possible, and learning from every experience we have."

To blame bad bat form?

Michael Keane (left) and Harry Maguire (center) played in the middle of England's four-man defense on Friday

Maguire, who lined up alongside Everton's Michael Keane in central defense in Prague, believes that some of the English players' poor club form could have contributed to the below-average performance against the Czech Republic.

Maguire's Manchester United is 12th in the Premier League after a disappointing start to the season, while Keane's side Everton have lost five of their first eight games.

When asked whether there was a lack of trust in the English defense, Maguire replied, "Yes, maybe.

"It's a difficult game, of course, because you want to build partnerships, but sometimes you can not really do that internationally."

"But there are no excuses, we have to be better than Friday night, we have to go better, we have to be better on the ball and we definitely have to be better at keeping the ball off the net."