Prolate-oblate shape coexistence close to the ground state in the strongly-deformed proton-rich <math><mi>A</mi><mo>≈</mo><mn>120</mn></math> nuclei is reported for the first time. One of the four reported bands in $^{119}$Cs, built on a <math><mn>11</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>−</mo></mrow></msup></math> state at 670 keV, consists of nearly degenerate signature partners, and has properties which unequivocally indicate the strongly-coupled <math><mi>π</mi><msub><mrow><mi>h</mi></mrow><mrow><mn>11</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>[</mo><mn>505</mn><mo>]</mo><mn>11</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>−</mo></mrow></msup></math> configuration associated with oblate shape. Together with the decoupled <math><mi>π</mi><msub><mrow><mi>h</mi></mrow><mrow><mn>11</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>[</mo><mn>541</mn><mo>]</mo><mn>3</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>−</mo></mrow></msup></math> band built on the <math><mn>11</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>−</mo></mrow></msup></math> prolate state at 110 keV, for which a half-life of <math><msub><mrow><mi>T</mi></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>=</mo><mn>55</mn><mo>(</mo><mn>5</mn><mo>)</mo><mspace width="0.25em"></mspace><mrow><mi>μ</mi><mtext>s</mtext></mrow></math> has been measured, the new bands bring evidence of shape coexistence at low spin in the proton-rich strongly deformed <math><mi>A</mi><mo>≈</mo><mn>120</mn></math> nuclei, a phenomenon predicted since long time, but not yet observed. Calculations using the particle-number conserving cranked shell model and two dimensional tilted axis cranking covariant density functional theory support and well reproduce the observed oblate and prolate coexisting low-energy states in $^{119}$Cs.

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