The second half was also a tense arm wrestle between the two teams and it looked as if second half substitute Joe Carlisle had secured the points with a long range sweetly struck penalty six minutes from time.
But back came Wasps and a slicing break from England scrum half Joe Simpson in the closing stages, after Worcester were guilty of giving away a penalty near halfway, saw them camp on the line before Birkett broke away and touched down to spark visiting celebrations and break home hearts.
The painful result left Worcester reflecting what could, and maybe should, have been and about the small margins of defeat.
However, Head Coach Richard Hill admitted after the game that his team did not have time to dwell on defeat and instead must regroup and refocus before the big game in Newcastle against the Falcons in seven days from now.
With so much at stake in the game on the resumption of league action, it was perhaps no surprise that tempers flared in the opening exchanges as both packs jostled for the ascendancy.
Visiting England hooker Steve Thompson, in his first game for Wasps, was greeted with ironic cheers as he his first saw him knock on while the Worcester pair of Errie Claassens and Miles Benjamin showed plenty of early willing as they chased down high hanging kicks.
A penalty at the fiercely contested breakdown saw Andy Goode take the chance to open his account as Warriors took a 3-0 lead early on.
With the home lineout under pressure and scrum failing to fire, Wasps started to gain the upper hand in terms of territory and possession as the half wore on. Robinson was also showcasing his array of kicking skills as he drilled balls into the corner to put the host's set piece under further strain.
Referee Greg Garner awarded a penalty against the home side after they dragged down a driving maul and Robinson slotted the resulting points to level up the scores on 14 minutes.
The game was being dominated by the boot, but Worcester did look to use width they had immediate success as, with Claassens rock solid under the high ball, play released Marcel Garvey who chipped ahead and then fed the rampaging Jake Abbott, after former Worcester man Hugo Southwell failed to gather.
Wasps were repeatedly looking at cross field kicks from Robinson to open up space for their wide men with Tom Varndell the target but failing to pick up the ball on the greasy surface.
A penalty for closing the gap at the lineout gave the visitors more field position and they opted for a scrum 20 metres out. The ball was lost by Varndell as he hacked ahead, but Garvey was harshly penalised for a nudge on Joe Simpson as they both jostled for the ball. Robinson, though, saw his kick fly wide.
Benjamin raced past a static Wade to a huge ovation while on the other wing Garvey showed all his strength and power to dump Varndell into touch as his opposite number looked to hand him off and out-pace him. Garvey was also strong under a high bomb from Southwell as both teams continued to play the game in the air with a kicking game dominating.
Robinson saw another penalty fall short before having the final word of a disjointed opening 40 minutes as he nudged over a drop goal in injury time to give his side a 6-3 interval lead.
Hill made a double half-time change as Joe Carlisle and Aleki Lutui entered the game as Warriors looked to kick-start their game.
It appeared to work as Carlisle produced a gem of a kick to force Wasps back before his pass was skillfully pulled under his spell by Benjamin. The young fly half almost then sent Neil best clear as he attacked the Wasps defensive line at pace.
A horribly sliced clearing kick from Simpson piled more heat on Wasps and just when it looked like a penalty was coming it duly arrived as Wasps pulled a driving lineout down and Carlisle did the rest to draw the teams level.
A spilled pass from Abbott gave Wasps position after intense home pressure for over ten minutes and the scrum was then shoved forward to give Robinson an easy penalty kick to again put the Londoners ahead.
Worcester were now looking to looking to run the ball and not just kick for territory and Garvey's superb high catch proved crucial as Wasps needlessly swarmed over the top of the ball and gave Warriors a penalty of their own that Carlisle stroked over.
Adam Balding replaced James Percival, while Chris Jones moved to the second row, as the game swung from end to end with Benjamin adjudged to have produced a high tackle on Robinson when it appeared the fly half had slipped into his tackle.
The game was being played on a knife edge in the final quarter as both teams opted to play for territory knowing one moment of magic would almost certainly win the game.
Worcester thought they had done just that when Carlisle and Dale Rasmussen showed real bravery to run the ball from deep after Garvey had broken the London line and Abbott popped up on his shoulder to make big yards.
The penalty was then secured for the home side at the breakdown as Wasps were guilty of coming in at the side and ice-cool Carlisle smashed over a long range effort for the lead with five minutes left.
The home crowd were now getting louder and louder with every passing moment before a penalty on halfway for not rolling away gave Wasps the ball and one last chance to mount an attack and snatch the game.
Simpson made it count in decisive fashion as his clever break resulted in massive pressure on the home line as Worcester frantically tried to repel wave after wave of attack before Birkett stole a yard to blast over and silence Sixways.
The try sparked wild celebration from Wasps and despite Robinson missing his conversion, as it was charged down, the home side could not win the ball back from the kick-off as the visitors closed the final few seconds of the game out.
05m Goode p 3-0
14m Robinson p 3-3
40m Robinson dg 3-6
47m Carlisle p 6-6
51m Robinson p 6-9
57m Carlisle p 9-9
74m Carlisle p 12-9
78m Birkett t 12-14
Worcester Warriors: 01 Matt Mullan, 02 Chris Fortey (Lutui 40), 03 Tevita Taumoepeau, 04 James Percival (Balding 67), 05 Craig Gillies, 06 Neil Best, 07 Jake Abbott, 08 Chris Jones, 09 Shaun Perry, 10 Andy Goode (Carlisle 40), 11 Miles Benjamin, 12 Dale Rasmussen, 13 Alex Grove, 14 Marcel Garvey, 15 Errie Claassens
Replacements: 16 George Porter, 17 Aleki Lutui, 18 Oliver Tomaszczyk, 19 Adam Balding, 20 Sam Betty, 21 Ollie Frost, 22 Joe Carlisle, 23 Chris Pennell