Jurgen Klopp revealed Liverpool defender Joel Matip suffered a "only a little tear" in his thigh muscle in Sunday's friendly against Borussia Dortmund.
The centre-back was withdrawn midway through the first half of his side's 3-1 defeat in the International Champions Cup clash in Charlotte.
The sight of Matip limping off sparked fears he had suffered a reoccurrence of the thigh injury which ruled him out of the latter stages of the 2017-18 season, including the Champions League final.
While Klopp confirmed that was not the case, the German conceded the severity of the setback was unclear at this stage.
"It's not the same injury, it's another muscle, but it's a muscle, obviously. It looks like, hopefully, only a little tear," the Liverpool manager said.
"We cannot say more about this now, but that's of course the most negative thing about the day. It's not cool.
"These things can happen but you don't want them to happen. Maybe tomorrow or the day after tomorrow, we will know more. At this moment we only know that it was too painful to carry on."
Matip's fitness is a concern ahead of the new season, with Liverpool hosting West Ham in their Premier League opener on August 12.
Klopp was more upbeat over Daniel Sturridge, however, as the forward impressed in his 45-minute outing against Dortmund.
The Reds boss suggested the 28-year-old, who spent the second half of last season on loan at West Brom, still has an important role to play at Anfield.
"Who doubts Daniel Sturridge when he is fit? I don't. Outstanding player, hopefully he can stay fit and then the future is bright," Klopp said.
"He's young enough, it’s not like he's 30-something. He’s still in his 20s, so that's good. He’'s experienced as well, and has this kind of natural arrogance on the pitch which is good.
"If he tries something and it doesn't come off, he is not out of the game for 10 minutes. He stays in the game, and it is good for us to have him around."
|Collins trounces 2016 Aus Open champion Kerber|
|Sanchez: Man United thriving thanks to Solskjaer|
|Sharapova crashes out of Australian Open|
|Devils´ Palmieri replaces Hall on NHL All-Star roster|
|Tuchel stunned by PSG´s nine-goal thrashing of Guingamp|
|Modric wants to extend Real Madrid stay|
|Marotta: Icardi will re-sign, Godin wants Inter|
|´F*** no!´ - Westbrook on if he´s cool with Embiid|
|Mickelson shoots 66 to stay ahead at Desert Classic|
|Real Madrid? You never know what the future holds - PSG´s Mbappe|
|Inter lacked quality in disappointing Sassuolo draw - Spalletti|
|Walton has one goal for Lakers-Rockets matchup: Keep Harden under 50 points|
|CAF Champions League Review: Simba learn Vita lesson as Sundowns find form|
|Bayliss relishing pressure of World Cup and Ashes to finish England reign|
|Guardiola keen to keep City rhythm and challenge on four fronts|
|Fifita backs Johnson to inspire the Sharks|
|For Real Madrid, nothing is impossible - Solari refuses to give up in title race|
|Inter 0 Sassuolo 0: Spalletti´s side labour at sparse San Siro|
|Marshawn Lynch will continue playing ´if it works out´|
|Simeone excited by improving Atleti|
|Jones ´cautiously optimistic´ over Farrell ahead of Ireland clash|
|Sarri questions Chelsea motivation after Arsenal surrender|
|Emery urges Arsenal to find balance after downing Chelsea|
|Koscielny hails Arsenal fighting spirit in Chelsea win|
|Pellegrini: It was not a good idea for Arnautovic to play|
|Iran v Oman: We´re not satisfied yet, says Al Mahaijri|
|Carbery sends Munster through and ends Exeter´s lingering Champions Cup hopes|
|Dyche defiant despite offside call|
|Hasenhuttl rates Everton win as Southampton´s best|
|Benitez looking up the table after Schar inspires win over Cardiff|
|RB Leipzig 0 Borussia Dortmund 1: Witsel restores six-point cushion|
|Swansea City 1 Sheffield United 0: McBurnie punishes wasteful Blades|
|Cardiff sign Sala from Nantes for club-record fee|
|Arsenal 2 Chelsea 0: Lacazette and Koscielny fire Gunners to rousing derby win|
|Huesca 0 Atletico Madrid 3: Dominant Atleti keep pressure on Barca|
|Rashford arguably league´s best striker with Kane out - Solskjaer|
|Hafeez plays steady hand as Pakistan punish Proteas´ patient approach|
|Klopp: Exceptional Salah would have scored even more up front!|
|Suspected ´serious´ Verratti injury leaves Tuchel with mixed emotions|
|We needed to rediscover our best form - Ramos pleased for Real Madrid fans|
|City bought Guardiola four full-backs! - Mourinho aims dig at Man Utd transfer policy|
|Valverde ´not frustrated´ amid De Jong & Vela links|
|Championship Review: Leaders Leeds beaten at Stoke as Villa end Hull run|
|Bournemouth rode their luck, admits Howe|
|Barca boss Valverde calls for clarity on RFEF rules|
|Bears rack up 107 points in routing Enisei en route to quarter-finals|
|Paris Saint-Germain 9 Guingamp 0: Verratti injured for rampant champions|
|Solskjaer: I´ll remember managing United for the rest of my life|
|Palace win a ´massive relief´ for Liverpool boss Klopp|
|Salah fourth fastest to 50 goals in Premier League history|
|Real Madrid 2 Sevilla 0: Solari´s side take over third spot|
|Watford 0 Burnley 0: Wood denied winner by contentious call|
|Liverpool 4 Crystal Palace 3: Salah reaches 50 thanks to Speroni shocker|
|Newcastle United 3 Cardiff City 0: Schar double moves hosts out of bottom three|
|Southampton 2 Everton 1: In-form Saints steer clear of trouble|
|Bournemouth 2 West Ham 0: Wilson and King sink Pellegrini´s men|
|Manchester United 2 Brighton and Hove Albion 1: Record-breaking win for Solskjaer|
|Pelicans star Anthony Davis out for one to two weeks with sprained finger|
|Verratti hobbles off for PSG against Guingamp|
|Brook ponders next move after missing out on Khan|
|Mick Schumacher: The Ferrari academy graduates who made it to F1|
|Thailand v China: Lippi aims to overcome War Elephants and reach last eight|
|I deserved red card, says Wolves boss Nuno|
|Mick Schumacher joins Ferrari Driver Academy|
|Jared Goff not worried about Superdome noise: ´When it´s loud, we love it´|
|Rooney urged Rashford to run at defenders|
|Former Springbok Lambie retires from rugby aged 28|
|Spygate: EFL confirms 11 clubs have made contact about Leeds|
|When it´s loud, we love it - Goff ready for New Orleans noise|
|Wolves 4 Leicester City 3: Jota hat-trick drama piles pressure on Puel|