How can I set the default Value on a custom SelectOption List?

Question

The Following works good to retrieve my account list in a SelectList on my VF.
But I'm trying to set a specific Default Account as the first value in the list - Now it shows up last..
*Is there any way to choose a specific Value (based on any Criteria I choose) from my account List and set as Default on my SelectList ?? *

Controller :

public List<Account> matchingAccounts          = new List<Account>();
public List<SelectOption> accountSelectOptions = new List<SelectOption>();
public String matchAccountId                 {get;set;}
public String accountName                    {get;set;}

public List<SelectOption> getAccountSelectOptions()     { 
    matchingAccounts = [Select Id,Name From Account WHERE Name LIKE : accountName];
    if(matchingAccounts!=null) {
         for(Account acc:matchingAccounts){
             if(acc.myDefault__c) {
             accountSelectOptions.add(new SelectOption(acc.Id, acc.Name));

             //Setting as Default Value - FIXED...
             matchAccountId =  acc.Id;
             }
             else {
              accountSelectOptions.add(new SelectOption(acc.Id, acc.Name));
             }
            } 
    else {
         accountSelectOptions.add(new SelectOption('New','New Account: '+pot.Account_Name__c));
          }
    return accountSelectOptions;
  }

VF Page :

<apex:selectList label="Account Name" value="{!matchAccountId}" size="1" required="true">
      <apex:selectOptions value="{!accountSelectOptions}"/>
      <apex:actionSupport event="onchange" reRender="thePageBlock" action="{!showHideRTSelect}"/>
</apex:selectList>

Answer 1

Yes, set the default value on matchAccountId. The Select List should initialize with that value as selected.