BBC Sport's Aadam Patel reports on the latest from the Liverpool tour of the United States.

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.