Liverpool won two games and lost one during their pre-season tour of the USA. Andoni Iraola's verdict after Liverpool's 4-2 defeat to Leeds in Chicago on Sunday was telling. "Obviously it's not the result you want but I think [it was] probably the most useful friendly we played," he said. "In a positive way in the first half and in a negative way in the second half. We've learned a lot and I think we can take good conclusions and solve some things."

If something needs solving, then it is a problem and Liverpool require reinforcements at the back. In three matches in the USA, they conceded six goals but four of those came against Leeds in the space of 25 second-half minutes. Liverpool started that game with a backline of Jeremie Frimpong, Luke Chambers, Ifeanye Ndukwe and Milos Kerkez. They ended it with Calvin Ramsay, Mor Talla Ndiaye, Ndukwe and Kostas Tsimikas. Against Wrexham four days earlier in New York, a similarly youthful backline deserved credit for keeping a clean sheet. But against fellow Premier League opposition in Leeds and a solid top-flight striker in Dominic Calvert-Lewin, Liverpool were brutally cut open.

In fairness, Kerkez is the only one of those who you can class as an expected starter for the season ahead. Captain Virgil van Dijk is back in training but Liverpool do not have the depth to challenge seriously. In fewer than three weeks, Van Dijk will need a partner at centre-half when Liverpool start their Premier League campaign at Newcastle.

The worry for Iraola is that neither Joe Gomez or Giovanni Leoni will be available while new signing Jeremy Jacquet failed to play a minute on this tour as Liverpool continue to manage his return. Iraola has said repeatedly that his side are "thin" at the back, not helped by the departures of experienced defenders Andy Robertson and Ibrahima Konate. Jacquet and Leoni are huge talents but not proven and given his injury record, Gomez will not be able to paper over the cracks.

Liverpool ship four second-half goals to leave Iraola with much to ponder. Intensity, smiles & Lewandowski - inside Liverpool training under Iraola latest Liverpool news, analysis and fan views. Sporting director Richard Hughes was at the friendlies in Nashville and New York but not at the game on Sunday. He will know as much too. At the very least, Liverpool need to bring in at least one name that can play at centre-back and potentially at right-back, given Conor Bradley is still "way off" a return.

Arne Slot used Curtis Jones and Dominik Szoboszlai as emergency right-backs last season and that can't happen again. Ideally, they need someone with experience. "You have to ask the manager, not me," Szoboszlai said after the Leeds defeat on what his role in the team looks like going forward. "Last season I played a lot of positions. Let's see. Hopefully he puts me in midfield but if he needs me at right-back, happy to do that."

Former Liverpool captain Phil Thompson told BBC Sport in Chicago that Iraola will rely on more experienced players, both old and new. "You look back when Jurgen [Klopp] won the league and you had [strong class="player-name"]Jordan Henderson and [strong class="player-name"]James Milner. And a fantastic leadership group with Virgil, Alisson, Mo Salah and even Trent Alexander-Arnold went on to become a leader.

"That has dwindled. So you need new ones to come in. We've lost some good players so people need to step up. "That dressing room needs to be tight and they need to lay down some player rules. Because when you have a difficult time, they need strong voices. "Right now, there's only Virgil and Ali [Alisson]. Someone like Szoboszlai has to step up too and I think he will."

Bradley Barcola has scored 39 goals in 152 appearances for PSG. When BBC Sport spoke to Liverpool CEO Billy Hogan in New York, the message was very much that FSG will continue to invest when it comes to doing what is best to put the team in a place to win. With Szoboszlai, Ryan Gravenberch and Alexis Mac Allister, Liverpool have solid options in midfield.

Szoboszlai and Gravenberch signed new contracts this year while Iraola will be hoping to get the best out of Mac Allister, who was nowhere near his best last season. Curtis Jones' move to Inter Milan looks to be edging closer with Liverpool open to a sale around the £35m mark. Any move will also depend on the future of Trey Nyoni, 19, who has had an excellent pre-season.

There is positive news in that both Wataru Endo and Stefan Bajcetic are back in training while Harvey Elliott's next steps also remain to be seen. Liverpool enquired about Adam Wharton earlier in the year but they are not the only club interested in the Crystal Palace midfielder.

One department where at least one more signing is guaranteed is up front, with PSG'S Bradley Barcola now Liverpool's primary target after they missed out on Yan Diomande. Liverpool have already signed Victor Munoz from Osasuna for £34m. It would be unfair to tag Barcola as the direct replacement for Mohamed Salah but with PSG valuing him at £145m, it would be a statement signing.

Liverpool are more willing to do a deal at about £100m, with Barcola open to a move to Anfield. Given the departure of Salah, expect to see more of 17-year-old Rio Ngumoha down the right flank. Ngumoha looked a lot more comfortable down his preferred left against Leeds but he has the attributes to be a force down both sides for a manager who wants his wingers to be able to play on either flank.

Alexander Isak and Florian Wirtz made encouraging starts to their pre-season but a decision needs to be made on Federico Chiesa, who wants to fight for his place at Liverpool despite links with a return to Italy. Kieran Morrison, 19, had a good tour, scoring the first goal of the Iraola era and depending on depth, the expectation is that he will likely go on loan this season.

More youngsters will be loaned out over the coming weeks. In June, BBC Sport reported that Tottenham were among a number of clubs monitoring Cody Gakpo's situation but such a move would only take place if Liverpool have a replacement and given he has four years left on his contract, the Netherlands international would not come cheap.

Liverpool still view him as a proven attacker in the Premier League who can function in different ways and with Hugo Ekitike unlikely to feature this year because of a ruptured Achilles tendon, letting Gakpo go would be a big call. Mike Gordon, the FSG president and essentially the managing owner of Liverpool, was in Chicago on Sunday. Like everyone else associated with the club, he would have seen the excitement for the Iraola era in full flow in the first half before the realisation after the break this squad is in need of more incomings.