There are some preterite verbs in Spanish which are not necessarily irregular but do have a spelling change.
-AR verbs whose stems end in the letters C, G and Z have spelling changes in the YO form.
While these verbs are used regularly in speech, the rules of Spanish spelling require that the sounds "k", "g" and "s" (written z) be written differently before E and I:
Por ejemplo:
| YO FORM | INFINITIVE | TRANSLATION |
| Yo jugué | (jugar) | I played |
| Yo llegué | (llegar) | I arrived |
| Yo pagué | (pagar) | (I paid) |
| Yo practiqué | (practicar) | (I practised) |
| Yo saqué | (sacar) | I took |
| Yo toqué | (tocar) | (I touched / ply (instrument) |
| Yo empecé | (empezar) | I started |
| Yo almorcé | (almorzar) | I had lunch |