note : some may consider portions of the following text to be spoilers . 
be forewarned . 
james toback's return to directing after a eight-year layoff , two girls and a guy , is a film which is comprised , more or less , of just that : one guy , blake ( robert downey jr . ) ; two girls , carla ( heather graham ) and lou ( natasha gregson wagner ) ; one primary setting ( blake's absurdly spacious bachelor apartment ) , and a great deal of dialogue . 
embracing a near real-time approach , this is a highly theatrical feature that completely hangs upon the performances of its three actors and the quality of the dialogue written by mr . toback for his bantering characters . 
fortunately , the film's cast is up to the challenge , and the wordy exchanges between the triad of characters , while admittedly variable , are occasionally wickedly amusing . 
the film's setup is fairly generic in nature , and opens rather unpromisingly . 
we meet self-possessed blonde carla and feisty brunette lou , both waiting outside a soho loft . 
as they engage in idle chatter , it is revealed that they're both waiting for their respective boyfriends to return from the airport , and it doesn't take long for them to come to the realisation that they're being two-timed by the same guy . 
more indignant with him than catty with each other , the duo break into blake's loft and await his arrival for a confrontation . 
it's when blake returns to his abode where the film hits its stride . 
played with magnificent bombast by mr . downey jr . , blake is a cad , all right , but a captivatingly dynamic , blusterous , and stealthy piece of work that bursts onto the scene and raises the stakes to new heights . 
it's fascinating to watch this character in his natural habitat , and perhaps the film's best choice was to have his two girlfriends scamper off into hiding upon his return , allowing us to size up blake not with his interactions with others , but by his own innate behaviour . 
whether he's flamboyantly behind his piano in a rollicking rendition of vivaldi , or on the phone leaving messages to his beloveds ( carla , lou , and his unseen sickly mother ) , it's never less than wildly entertaining and insightful . 
though at this point i almost hoped the film would transform into a one-man show -- a typical afternoon in the life of blake , if you will -- carla , and then lou , reveal themselves , and the sparks begin to fly . 
 ( one of the great touches in the film is how blake , when startled by carla's unannounced appearance , begins to both verbally and physically backpedal even before he realizes that the cat's out of the bag . ) 
double-teamed by the understandably aggrieved women ( who are more smirkingly inquisitive than ferociously vengeful -- they want a justification for his ongoing hypocrisy ) , an increasingly-flustered blake weakly defends himself with apologetic and even self-righteous declarations against their verbal jabs . 
surprisingly delightful in the waltz of scathing witty banter shared by its trio of characters , two girls and a guy concludes its first sequence with an unexpected apoplectic act of such outrageous audacity that it seemed nothing was off-limits for this film . 
however , it'd be unfeasible to attempt to string along carla and lou's outrage to full feature-length , and it's as the movie gradually transforms into the sharing of exploratory profundities on the nature of fidelity and relationships that it slowly but surely begins to unravel . 
the dialogue becomes less and less engaging and clever , the film's tempo loses its liveliness , the dynamic between the characters evolves in unconvincing fashion , and several sequences fall flat . 
subtle and not-quite-subtle allusions are made ( a poster of jules et jim hangs prominently on the wall ) , and secrets are revealed which barrel the film toward an uncompelling weepy finale . 
one key turning point in the film is the kinky sex scene between blake and carla . 
two girls and a guy was embroiled in a bitter , long-running dispute with the mpaa with regards to this scene -- contractually-obligated to deliver an r-rated film , mr . toback was forced to resubmit fourteen scaled-down versions of the steamy interlude before the mpaa withdrew their nc-17 rating in favour of an r -- and while admittedly titillating , the net effect of the vignette on the film's thematic narrative is rather dubious . 
if anything , two girls and a guy serves as a showcase for the phenomenal talents of mr . downey jr . , whose versatility is put to the test in this film . 
he plays the gamut from indignant to humbled , from self-assured to disconcerted , yet his acting gears shift so smoothly as to not be registered . 
it's a wonderful performance in a role custom-tailored for him ; mr . toback wrote the screenplay in four days shortly after mr . downey jr . was arrested on drug charges , and it's hard not to see echoes of reality seeping into his character -- in a monologue to his mirrored reflection , blake's self-chiding to " get [his] shit together " is disquieting in its resonance . 
while mr . downey jr . 's showstopping performance is undoubtedly the primary strength of the film , both actresses are solid in more broadly-observed roles . 
ms . graham is quickly becoming one of america's more daring actresses , involving herself in three successive risky projects -- two girls and a guy and boogie nights are both quite sexually frank , while lost in space has a screenplay penned by akiva goldsman . 
she's quite appealing here , playing a character at once both dainty and sultry . 
meanwhile , ms . gregson wagner initially portrays lou with such an unwarranted spunk that audiences are likely to find it either annoying , or , like me , endearing . 
she tones it down substantially as the film progresses , but i found her more fun to watch as the artificially excitable chatterbox . 
the film was reportedly shot in eleven days , filmed mostly in sequence , and the resultant artifacts of this rapid shoot are evident throughout . 
two girls and a guy has an agile , spontaneous sort of feel , and one senses that mr . toback encouraged a good deal of improvisation from his three actors . 
while the film could be transposed directly to the stage more or less intact , it doesn't feel constricted ; the expansive apartment setting is well-used to vary the background , and mr . toback allows his camera to wander and linger on his characters in an effective manner . 
two girls and a guy falls short of its potential , but thanks to some stellar work by mr . downey jr . , it's still often an enjoyable , bitingly funny romp , particularly as we watch the surprisingly-resilient blake evasively try to rationalize his behaviour and even turn the tables on his girlfriends . 
 " i'm an actor , " he tells them at one point , using the ol' tried-and-tested occupational-hazard defense . 
 " actors lie . " 
but not , they all seem to agree , denzel washington .