It was 3-1 in the 80th minute when Ragnar Klavan's cross into the box was met by a towering header from Solanke, who finished his impressive preseason by scoring his third goal of the summer.
That will be signicantly cheaper than a move for Keita after RB Leipzig rejected a second bid of €75million (£66m) for the player last week.
"But it makes sense that they go there and see the team - they are really good", he added.
The 29-year-old former Southampton player could miss the first two months for Liverpool, and that comes as a deafening blow, as the Reds have Champions League play-off qualification in sight too, besides the Premier League. Lallana was a trusted piece of the squad for Klopp, making 31 appearances last season, with only four of them being off the bench, in the Premier League.
"Liverpool were by far the strongest team in the pot, but it is not as though I would have rather played against Napoli". He, of course, still has to adapt because he's not here too long, but you can already see what a threat he is going to be offensively.
In addition to Alvarez, the likes of Enric Saborit (groin), Mikel Rico (muscle injury) and Ander Iturraspe (leg) are also absent and are unlikely to start Bilbao's first league game against Getafe in two weeks' time.
The Merseyside boss made it clear that he would be closely watching the England international's progress and praised Lallana for his attitude.
"This pre-season has brought us new players".
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