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These include perturbations about a Kerr back- ground using the Teukolsky equations [33]. In addition, adding second-order perturbative corrections [34] should improve accuracy for larger mass ratios. Finally, given our encouraging first results, one can consider a phe- nomenological description of intermediate-mass-ratio in- spiral trajectories based on a series of detailed nonlinear numerical runs to model the tracks of BHBs as function of mass ratio and spins. The resulting phenomenologi- cal trajectories could then be used to efficiently generate accurate waveforms over a wide region of the parameter space. The benefits of this approach are apparent: i) No fitting parameters have been used in the generation of the waveforms. ii) Since perturbation equations natu- rally transition to close limit ones, i.e. source free wave equations, numerical tracks are not needed after merger, thus reducing the cost of the nonlinear simulations (in our example it represented a 40% reduction in running time.) iii) The perturbative evolution also provides a natural way to extract waveforms at very large radii in a well known and defined gauge, in a region accurately de- scribed by linear perturbations. Thus further cutting the size of the required numerical grid and hence the compu- tational cost of the nonlinear simulation. iv) The com- putation of even, odd, leading, and higher-order modes ( ℓ, m ) with the same black holes trajectory. Note that the small amplitude of the non-leading terms impose ad- ditional requirements of accuracy at the extraction radii and at the external boundaries of the full numerical grid to avoid interfering reflections. v) Perturbation codes are highly efficient and run within seconds on standard CPUs, and are also amenable for running in GPUs or other accelerated hardware opening up the possibility of generating online analysis of LIGO/VIRGO data. Conclusions and Discussion: Given the current dif- ficulties in efficiently solving the intermediate mass ratio regime by purely nonlinear numerical methods, we propose to use perturbation theory to propagate gravita- tional waves on a black hole background using trajectory information from a combination of nonlinear numerical and semi-analytic methods, such as the post-Newtonian approximation. In this letter we provided a ‘proof of principle’ comparison between our hybrid technique and fully nonlinear results in the most challenging case for perturbation theory, i.e. q = 1 / 10. of the binary evolution where they are needed.