Wales' World Cup qualification hopes were dented by a 0-0 draw against Estonia in Cardiff.
Estonia, ranked a lowly 110th in the world and sandwiched between Guinea-Bissau and North Korea, were bottom of Group E having conceded 15 goals in three games.
But Wales failed to break down stubborn visitors on a night when even skipper Gareth Bale, who was winning his 99th cap, was unable to rescue them and Belgium increased their lead at the top of the group with a 1-0 win over Belarus.
Bale had scored a hat-trick, including a stoppage-time winner, as Wales beat Belarus 3-2 in World Cup qualifying on Sunday.
The Real Madrid forward came as close as anyone to breaking the deadlock before a 21,624 crowd as fans returned to the Cardiff City Stadium in large numbers for the first time since the start of the coronavirus pandemic.
Bale's point-blank header was brilliantly saved by Estonia's Arsenal teenager Karl Jakob Hein before the Real Madrid forward headed against a post late on as Wales pressure intensified.
This was the first competitive match between the two nations with Wales having won friendlies in 1994 and 2009.
Wales had been buoyed by Sunday's dramatic victory against Belarus and interim boss Robert Page made three changes from that Kazan clash with Ethan Ampadu, Harry Wilson and Tyler Roberts recalled.
Estonia were without a point in World Cup qualifying but they had scored twice against Belarus, Belgium and the Czech Republic and Wales had to show more defensive resilience than in Kazan, especially in stopping the counter-attack.
Wales were almost ahead after 38 seconds when Bale's header allowed Roberts to lay the ball into the path of Chris Gunter.
The full-back sped down the right and his cross deserved a better finish than the one Wilson supplied as the Fulham forward slid the chance wide.
Wales dominated possession but were kept in check until Daniel James led a counter-attack for Roberts to set up Bale, whose effort curled high of the target.
Roberts also failed to test Hein from the next Wales attack while Estonia were quick to get bodies around the ball to smother Bale.
Wales might have been awarded a 25th-minute penalty when Marten Kuusk handled Wilson's cross but French referee Ruddy Buquet waved play on and the incident was not referred to VAR.
Wilson was forced off after taking a knock to the head and replaced by Jonny Williams, who had made a positive impact coming on as a second-half substitute against Belarus.
Wales breathed a huge sigh of relief after 38 minutes as Mattias Kait was invited to shoot from 20 yards and smacked the home crossbar.
Hein did not have a save to make in the first half but the 19-year-old produced a superb point-blank effort to stop Bale profiting from Ben Davies' free-kick.
Joe Morrell then released Roberts through the middle and Hein stuck out a foot to divert the striker's shot around the post.
Roberts soon made way for Mark Harris and the Cardiff striker's excellent movement posed problems for opponents who were appearing to run out of steam.
Hein held on to a Bale header, pushed out another effort from the Wales captain who sent the rebound onto the post and then tipped away Joe Allen's fierce drive.
Danny Ward stayed alert at the other end to deny Konstantin Vassiljev producing an Estonian sucker punch as Wales failed to score for the third time in four games.
