SANTA CLARA, Calif. -- Preparing for a third summer tournament in three years as Argentina's key man, and being called back to Europe to stand before a judge in his long-running tax case, it's no surprise Lionel Messi's back has given out.
Of course, the heavy kick he received in a friendly against Honduras 10 days ago did most of the damage, but the world's best player could be forgiven for buckling under the weight of expectation right now.
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After jetting from Los Angeles to Barcelona last Wednesday, giving evidence in Catalunya on Thursday, and rejoining his international teammates on the west coast on Friday, he practiced at the San Jose State University on Saturday but could only undergo light training on his own.
Argentina coach Tata Martino said on Sunday that he would wait right up until that afternoon's training session to see if he can call on Messi to start against Chile, but, on the available evidence, he surely will not be able to.
The No. 10 began the session - the short section open to the media - far from the cameras that had turned up to report on his progress. As the journalists were ushered out of sight, Messi once again left the main group to walk through some routine exercises.
Football teams are no strangers to a bit of open training kidology, but Argentina will surely have perfected the art if its talisman does make the starting lineup against La Roja after all: he just does not look ready.
That will mean Argentina heads into its biggest test of the group stage - and probably the biggest clash in any group - without its main man.
With Mexico, perhaps Argentina's biggest rival for the Copa America Centenario, putting in the best performance of the tournament so far on Sunday night, a gauntlet has been thrown down.
Chile is the holder of the competition, having won its first international trophy in 99 years last summer on home soil, and although the team not quite at the level it reached under the since departed Jorge Sampaoli, Juan Antonio Pizzi's men can still be expected to take the game to their vaunted opposition.
Although it will represent South America at next year's Confederations Cup, Chile will want to ensure it can enjoy CONMEBOL champion status for more than just 12 months. The nation heads into this tournament under the radar and without any major injuries, but you get the impression it will not be driven by the same intensity that delivered its historic success last time out.
Chile may not successfully defend its trophy, but it is certainly far from an ideal opening-day opponent for any side.
In the absence of Messi, Argentina will turn to Nico Gaitain - the Benfica playmaker perennially linked with Manchester United. But with Angel Di Maria, resurgent after a fine year in Paris, Sergio Aguero and Gonzalo Higuain also available, Martino certainly has the quality in attack to cope without the Barcelona forward, for the short-term at least.
Even so, what will once again prove most important this summer is desire within the squad. The two most recent winners of this tournament - Uruguay in 2011 and Chile in 2015 - fostered an unbreakable spirit that was insurmountable from the very outset (in the latter's case, it withstood Arturo Vidal nearly killing himself in a drunk-driving incident).
Uruguay, with the most balanced squad and spurred on by playing on Argentine soil, marched relentlessly to its 15th title five years ago, while Chile, in front of its own fans, knew its individual roles to a tee and executed them perfectly. In both cases, the heads and the hearts were in perfect harmony.
It is something that Brazil, always among the favorites, has not been close to matching in recent years and why the team is unlikely to end its 14-year trophy drought any time soon. In fact, this time around it looks to be Mexico, with an exciting squad and essentially playing at home, that will be there or thereabouts come the final in New Jersey on June 26.
But Argentina - ironically given its sparkling attack and ordinary defence - is not far from that ideal balance, either. It has come a long way since its 2011 horror show: the squad is together and they have a coherent game plan, meaning they are rightly expected to dispute their third consecutive final.
How they react to losing the last two will have a huge say in their fortunes over the coming weeks, but a fit and firing Messi could drag them to glory regardless. No pressure, Leo.