Anatoly Karatsuba discovered the Karatsuba algorithm in 1960, and reported it to Kolmogorov who published it under his (Karatsuba's) name without his knowledge. It seems fair to say that this first example of a "divide and conquer" algorithm eclipsed Karatsuba's 1966 thesis on "The method of trigonometric sums and intermediate value theorems".
For a physics example (from my own university) I note George Uhlenbeck, who with Goudsmit introduced the electron spin in a 1925 publication, while his 1927 Ph.D. thesisPh.D. thesis on quantum statistics was much less influential. (Here is the story how two Ph.D. students discovered the electron spin, which was missed by a giant like Pauli.)