The British and Irish Lions can only use the jetlag excuse once, according to All Blacks great Ian Jones.
The Lions laboured to a 13-7 win against the Provincial Barbarians on Saturday, three days after arriving in New Zealand.
Head coach Warren Gatland says the players were still struggling to adjust to the time difference.
"It's an easy cop out to say these guys are jetlagged," Jones told the BBC Rugby Union Weekly podcast.
"If you go down the line of [saying it's] a scratch side, with jetlag, you can use that excuse only once on a tour, ever. You cannot go back on that.
"They have known a long time out they were going to play this game, so they had to go through their professional routines to get them into sync."
The Lions already face a decisive week on the tour, with matches against the Blues on Wednesday and the in-form Crusaders on Saturday.
The schedule has been labelled "suicidal" by former New Zealand coach Graham Henry, but Jones says the itinerary is a "non-issue."
"Let's not worry about the brutality of this tour, because they have 41 players," added Jones, who played in 79 Tests for New Zealand between 1990 and 1999.
"So that's a non-issue. Don't even worry about how tough this tour is.
"With 15 players you can call it brutal, but they have 41 players remember, and a huge medical staff, so it shouldn't be raised."
Jones played alongside Lions boss Gatland throughout the 1990s, and was coached by his fellow Kiwi when a player at Wasps at the turn of the century.
"I back Warren Gatland wholeheartedly," Jones added.
"A) because I've been coached by the guy, B) because I've played alongside the guy and know what he means, and C) because he can get things right off the field.
"When you get things right off the field, it just translates to things on the field."
The Lions have embarked on a charm offensive with the New Zealand public so far on this trip, and on Sunday visited the Waitangi Treaty Grounds for an official Maori welcome, or pōwhiri.
Despite fears the Lions are putting too much stall in off the field commitments, Jones feels embracing the Kiwi culture will be crucial to success.
"What he's doing off the field in terms of getting his players out there to meet New Zealanders, understand what New Zealand rugby is all about, learning the culture; it's 100% important," Jones continued.
"Once the Lions players get into the mind of Gats, or get into the minds of the New Zealand public and understand what rugby means to us - playing a home - I think that's actually a really important thing."