Wales treated a record crowd of 5,455 at the Cardiff City Stadium to a dominant display as they thrashed Estonia 4-0 in the Welsh capital.
Angharad James' tidy finish gave Wales a narrow 1-0 lead at the interval.
Record scorer Helen Ward doubled Wales' lead after half time before Natasha Harding's tap-in made the result safe.
Wales kept pushing and ended the contest with over 30 shots on goal and added a late fourth when captain Sophie Ingle smashed home after a fine run.
Wales' dominant display capped another pleasing international break for Wales' women.
This was simply a must-win game for Grainger's charges as they look to secure at least a runners-up berth from World Cup qualifying group I.
Wales have never qualified for a major tournament, but have made a promising start in their bid to reach the 2023 World Cup in Australia and New Zealand.
Having thrashed Kazakhstan 6-0 in their opening game, Grainger's side ground out a 1-0 victory in Estonia before securing a creditable 1-1 draw in Slovenia last Friday as they look to keep pace with group leaders France.
Manager Gemma Grainger has been clear in her aims to make Wales a more attacking side and that policy was reflected in her starting XI with Ceri Holland switching from right wing to left back and Manchester United's talent teen Carrie Jones earning a start in attack.
Watford's Ward also earned a recall in place of the suspended Kayleigh Green, earning her 96th as Wales' record scorer looked to add to her goal tally.
Ward might have put Wales ahead as early as the 11th minute, but she just failed to connect with Harding's cross, while Harding herself failed to convert from a Karina Kork save as she looked to turn home a rebound.
Wales continued on the front-foot in a one-sided first half where they enjoyed 85% possession, but Kork saved efforts from distance from captain Sophie Ingle and Holland, while Harding drilled wide and Ward headed over.
The breakthrough arrived on 27 minutes when Ingle's perfect pass bisected Estonia's defence and Angharad James ran clear to slot home as she scored just her third Wales goal on her 90th appearance.
Wales pushed for a second before the interval, but Harding shot tamely at Kork and saw her cross evade both Gemma Evans and Jones by a matter of inches, before Ingle and Ward both glanced headers just wide.
The wait for a second goal did not last long though, with Ward scoring her 44th international goal on 48 minutes as she slipped the ball under Kork after Rhiannon Roberts' threaded through ball.
The cushion eased Wales nerves and Harding soon added a third from close-range after Holland's teasing cross.
How many goals Wales could score became the only issue at 3-0 and with the match won and Grainger opted to give a debut to Hannah Cain, the Leicester midfielder who has switched allegiances from England.
Wales' pressure never relented and Harding was denied a second by a last-ditch tackle, before Roberts headed straight at Kork.
The chances kept coming but Cain's firmly-struck volley was pushed over by Kork and Jones' superb run and cross deserved more, but Harding just failed to make telling contact.
Harding might have score a hat-trick at least on another night, but she was again denied by Kork, who deserves immense credit for keeping the score respectable on a night where Wales had 80% possession and a total of 32 shots.
However, they were not to be denied a late flourish and Ingle scored the pick of the goals on the night as she beat two defenders before slamming home.
Player of the match: Karina Kork, Estonia, the visiting goalkeeper kept the score respectable.
Formation 4-2-3-11O'SullivanSubstituted forClarkat 87'minutes5Roberts14Ladd3Evans18HollandSubstituted forFilbeyat 87'minutes8James4Ingle11Harding10Fishlock20JonesSubstituted forWoodhamat 77'minutes7WardSubstituted forCainat 61'minutes
Formation 5-4-112Kork6OravSubstituted forSaarat 81'minutes9Aarna15Zlidnis16Liir7Merisalu13Bannikova8MengelSubstituted forNiitat 59'minutes10Daut19Kubassova23TreibergSubstituted forSaarat 86'minutes
Referee:Marta Frías Acedo
Match ends, Wales Women 4, Estonia Women 0.
Second Half ends, Wales Women 4, Estonia Women 0.
Goal! Wales Women 4, Estonia Women 0. Sophie Ingle (Wales Women) left footed shot from the centre of the box to the centre of the goal.
Foul by Hannah Cain (Wales Women).
Eva-Maria Niit (Estonia Women) wins a free kick in the defensive half.
Corner, Wales Women. Conceded by Marie Saar.
Substitution, Wales Women. Olivia Clark replaces Laura O'Sullivan.
Substitution, Wales Women. Anna Filbey replaces Ceri Holland.
Corner, Wales Women. Conceded by Sandra Liir.
Attempt missed. Angharad James (Wales Women) right footed shot from the left side of the box misses to the right. Assisted by Sophie Ingle.
Substitution, Estonia Women. Heleri Saar replaces Emma Treiberg.
Attempt blocked. Natasha Harding (Wales Women) right footed shot from the centre of the box is blocked. Assisted by Sophie Ingle with a through ball.
Attempt missed. Rhiannon Roberts (Wales Women) right footed shot from the centre of the box misses to the right. Assisted by Angharad James with a cross following a corner.
Corner, Wales Women. Conceded by Sandra Liir.
Substitution, Estonia Women. Marie Saar replaces Maria Orav because of an injury.
Attempt saved. Ceri Holland (Wales Women) right footed shot from the right side of the box is saved in the top centre of the goal.
Attempt blocked. Jess Fishlock (Wales Women) right footed shot from the centre of the box is blocked. Assisted by Natasha Harding.
Substitution, Wales Women. Lily Woodham replaces Carrie Jones.
Offside, Wales Women. Carrie Jones tries a through ball, but Natasha Harding is caught offside.
Offside, Wales Women. Sophie Ingle tries a through ball, but Jess Fishlock is caught offside.