In the present tense, I would say "No sé si pueda jugar", using the subjunctive "pueda". However, I saw this sentence:

Yo recuerdo que cuando íbamos al hospital, estaba preocupado porque ese sábado teníamos un partido de fútbol y no sabía si iba a poder jugar.

Here, the indicative "iba" is used. Can "fuera" be used instead, and why is indicative allowed in this case?

The sentence is from the following Duolingo podcast: https://podcast.duolingo.com/episode-1-the-duolingo-spanish-podcast-adc1f8c8b79e.

  • Most dialects of Spanish would say "No sé si puedo jugar", actually. I only recently encountered a native who would say pueda (he was from Mexico). Apr 7, 2018 at 22:29
  • @guifa - I have never heard that in Mexico, personally. // I guess we are assuming the first sentence is not talking about some other person, right? Apr 7, 2018 at 23:45
  • I find it difficult to discuss Spanish in English, but nevertheless. No sé si voy a poder jugar: I don't know if I am going to be able play [future meaning] versus,the past of that: No sabía si iba a poder jugar: I didn't know if I was going to be able to play. Iba a poder jugar is the past for voy a poder jugar + verb. The subjunctive in this case is not relevant. "poder jugar" is not "ir + a poder + verb (to be going to be able to, in English).
    – Lambie
    Apr 8, 2018 at 15:14

2 Answers 2


In general, when negating, you will use indicative with saber and keep the subjuntive for creer, but that's not a hard-and-fast rule. Your example using the subjunctive in the present is correct, but the indicative would be correct as well, and it may be more common. The indicative just states the speaker doesn't know; the subjunctive adds a hint of doubt.

In your example in the past tense, the speaker is stating the fact that he didn't know whether he would be able to play. There's no doubt there; he is aware that he does not know (and possibly cannot know until the doctor sees him in the hospital). In this context, if he wanted to show some doubt, he would use the conditional mood: «no sabía si iría a poder jugar» (or simply: «no sabía si podría jugar»). Note that the conditional is here employed both in this sense and as the "future of past" tense.

You cannot use fuera as in «no sabía si *fuera a poder jugar». It's ungrammatical. You could use the subjunctive to show belief or doubt using creer: «no creía que fuera a poder jugar». That's a different meaning, though: it means that the speaker believed he wouldn't be able to play.


Generally, the subjunctive is not used with "saber," whether it's present tense ("No sé si puedo jugar") or past tense ("No sabía si iba a poder jugar"). Before I say more about that, let's first review what the subjunctive does and in what situations it's appropriate. Wikipedia in English says:

The subjunctive is a grammatical mood (that is, a way of speaking that allows people to express their attitude toward what they are saying) found in many languages. Subjunctive forms of verbs are typically used to express various states of unreality such as wish, emotion, possibility, judgment, opinion, obligation, or action that have not yet occurred.

Subjunctives occur most often, although not exclusively, in subordinate clauses, particularly that-clauses. Examples of the subjunctive in English are found in the sentences "I suggest that you be careful" and "It is important that she stay by your side." (The corresponding indicative forms of the verbs in bold would be are and stays.)

Wikipedia in Spanish says:

Toma el carácter subjetivo de posible, probable, hipotética, creída, deseada, temida o necesaria.

With "saber," the subjunctive would sound pompous to my ear.

If there is uncertainty, doubt or disbelief, such as "No creo que llueva," "No creo que vaya a llover," "Dudo que llueva," etc., then the subjunctive is used. Also, the famous connecting "que" mentioned in Wikipedia clues us in that the subjunctive will probably be a good fit.

In "No sé si puedo ir" and "No sé si va a llover," I will either be able to go or I won't be able to go; it will rain or it won't. I don't know yet what's behind Door #2.

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