How to auto select (show) the first value of combobox in Ext Js?

Generally, when I want to select the first value of a store, I use this methods:

xtype: 'combo', 
fieldLabel: 'prov',
id : 'lang', 
store:[['tr','Türkçe'],['ru','Русский'],['en','English']],
mode: 'local',
triggerAction: 'all',
selectOnFocus:true,
listeners: {
    afterrender: function(combo) {
        var recordSelected = combo.getStore().getAt(0);                     
        combo.setValue(recordSelected.get('field1'));
    }
}