Latvia head coach Luca Banchi warned his players to beware of "fake friends" after they added defending champions Spain to their giant-killing conquests at the Basketball World Cup on Friday.

The tournament debutants stunned world and European champions Spain 74-69 in their second-round opener in Jakarta, after beating Tokyo Olympics silver-medallists France in the group stage.

Latvia's achievements have made them superstars in their home country but Banchi cautioned that they were "in a risky moment" with a place in the quarter-finals up for grabs.

"After France, too many people around talking, texting, social -- this is time for fake friends," he said.

"I really wish that the guys will stay humble and they will approach the next game with the same will and desire as they did since the beginning of our adventure."

Latvia looked to be heading for defeat when Spain took a 58-47 lead into the end of the third quarter.

But the Baltic team refused to be beaten and outscored the defending champions 27-11 in the final quarter to claim the win.

Latvia play Brazil in their final second-round game on Sunday and have a chance to make it through to the quarter-finals.

Power forward Davis Bertans, who led Latvia in scoring with 16 points, said beating Spain could "definitely not" compare to their 88-86 win over France.

"That game against France put us in a situation we've never been in before," he said.

"If we're not able to compete at this level against Brazil and come up with the win in that game, this doesn't really matter that much."

Spain took a perfect record into the game having won all three of their first-round matches.

Head coach Sergio Scariolo said he was happy with his players' attitude despite the final score.

"We know which are our strengths and which are our weaknesses, which showed a little bit more tonight, but the will was there," he said.

"In the last quarter we let them play too easy and we didn't move the ball well enough."

amk/leg